~drizzle-trunk/drizzle/development : contents of drizzled/sql

~drizzle-trunk/drizzle/development : (revision 1235)
/* Copyright (C) 2000-2003 MySQL AB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#define DRIZZLE_LEX 1
#include <drizzled/server_includes.h>
#include <mysys/hash.h>
#include <drizzled/db.h>
#include <drizzled/error.h>
#include <drizzled/nested_join.h>
#include <drizzled/query_id.h>
#include <drizzled/sql_parse.h>
#include <drizzled/data_home.h>
#include <drizzled/sql_base.h>
#include <drizzled/show.h>
#include <drizzled/plugin/info_schema_table.h>
#include <drizzled/function/time/unix_timestamp.h>
#include <drizzled/function/get_system_var.h>
#include <drizzled/item/cmpfunc.h>
#include <drizzled/item/null.h>
#include <drizzled/session.h>
#include <drizzled/sql_load.h>
#include <drizzled/lock.h>
#include <drizzled/select_send.h>
#include <drizzled/plugin/client.h>
#include <drizzled/statement.h>
#include <drizzled/statement/alter_table.h>
#include "drizzled/probes.h"

#include "drizzled/plugin/logging.h"
#include "drizzled/plugin/info_schema_table.h"

#include <bitset>
#include <algorithm>

using namespace drizzled;
using namespace std;

/* Prototypes */
bool my_yyoverflow(short **a, YYSTYPE **b, ulong *yystacksize);
static bool parse_sql(Session *session, Lex_input_stream *lip);
static void mysql_parse(Session *session, const char *inBuf, uint32_t length,
                 const char ** found_semicolon);

/**
  @defgroup Runtime_Environment Runtime Environment
  @{
*/

extern size_t my_thread_stack_size;
extern const CHARSET_INFO *character_set_filesystem;

const LEX_STRING command_name[COM_END+1]={
  { C_STRING_WITH_LEN("Sleep") },
  { C_STRING_WITH_LEN("Quit") },
  { C_STRING_WITH_LEN("Init DB") },
  { C_STRING_WITH_LEN("Query") },
  { C_STRING_WITH_LEN("Shutdown") },
  { C_STRING_WITH_LEN("Connect") },
  { C_STRING_WITH_LEN("Ping") },
  { C_STRING_WITH_LEN("Error") }  // Last command number
};

const char *xa_state_names[]={
  "NON-EXISTING", "ACTIVE", "IDLE", "PREPARED"
};

/**
  Mark all commands that somehow changes a table.

  This is used to check number of updates / hour.

  sql_command is actually set to SQLCOM_END sometimes
  so we need the +1 to include it in the array.

  See COMMAND_FLAG_xxx for different type of commands
     2  - query that returns meaningful ROW_COUNT() -
          a number of modified rows
*/
bitset<CF_BIT_SIZE> sql_command_flags[SQLCOM_END+1];

void init_update_queries(void)
{
  uint32_t x;

  for (x= 0; x <= SQLCOM_END; x++)
    sql_command_flags[x].reset();

  sql_command_flags[SQLCOM_CREATE_TABLE]=   CF_CHANGES_DATA;
  sql_command_flags[SQLCOM_CREATE_INDEX]=   CF_CHANGES_DATA;
  sql_command_flags[SQLCOM_ALTER_TABLE]=    CF_CHANGES_DATA | CF_WRITE_LOGS_COMMAND;
  sql_command_flags[SQLCOM_TRUNCATE]=       CF_CHANGES_DATA | CF_WRITE_LOGS_COMMAND;
  sql_command_flags[SQLCOM_DROP_TABLE]=     CF_CHANGES_DATA;
  sql_command_flags[SQLCOM_LOAD]=           CF_CHANGES_DATA;
  sql_command_flags[SQLCOM_CREATE_DB]=      CF_CHANGES_DATA;
  sql_command_flags[SQLCOM_DROP_DB]=        CF_CHANGES_DATA;
  sql_command_flags[SQLCOM_RENAME_TABLE]=   CF_CHANGES_DATA;
  sql_command_flags[SQLCOM_DROP_INDEX]=     CF_CHANGES_DATA;

  sql_command_flags[SQLCOM_UPDATE]=	    CF_CHANGES_DATA | CF_HAS_ROW_COUNT;
  sql_command_flags[SQLCOM_INSERT]=	    CF_CHANGES_DATA | CF_HAS_ROW_COUNT;
  sql_command_flags[SQLCOM_INSERT_SELECT]=  CF_CHANGES_DATA | CF_HAS_ROW_COUNT;
  sql_command_flags[SQLCOM_DELETE]=         CF_CHANGES_DATA | CF_HAS_ROW_COUNT;
  sql_command_flags[SQLCOM_REPLACE]=        CF_CHANGES_DATA | CF_HAS_ROW_COUNT;
  sql_command_flags[SQLCOM_REPLACE_SELECT]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT;

  sql_command_flags[SQLCOM_SHOW_STATUS]=      CF_STATUS_COMMAND;
  sql_command_flags[SQLCOM_SHOW_DATABASES]=   CF_STATUS_COMMAND;
  sql_command_flags[SQLCOM_SHOW_OPEN_TABLES]= CF_STATUS_COMMAND;
  sql_command_flags[SQLCOM_SHOW_FIELDS]=      CF_STATUS_COMMAND;
  sql_command_flags[SQLCOM_SHOW_KEYS]=        CF_STATUS_COMMAND;
  sql_command_flags[SQLCOM_SHOW_VARIABLES]=   CF_STATUS_COMMAND;
  sql_command_flags[SQLCOM_SHOW_WARNS]= CF_STATUS_COMMAND;
  sql_command_flags[SQLCOM_SHOW_ERRORS]= CF_STATUS_COMMAND;
  sql_command_flags[SQLCOM_SHOW_ENGINE_STATUS]= CF_STATUS_COMMAND;
  sql_command_flags[SQLCOM_SHOW_PROCESSLIST]= CF_STATUS_COMMAND;
  sql_command_flags[SQLCOM_SHOW_CREATE_DB]=  CF_STATUS_COMMAND;
  sql_command_flags[SQLCOM_SHOW_CREATE]=  CF_STATUS_COMMAND;

   sql_command_flags[SQLCOM_SHOW_TABLES]=       (CF_STATUS_COMMAND |
                                               CF_SHOW_TABLE_COMMAND);
  sql_command_flags[SQLCOM_SHOW_TABLE_STATUS]= (CF_STATUS_COMMAND |
                                                CF_SHOW_TABLE_COMMAND);
  /*
    The following admin table operations are allowed
    on log tables.
  */
  sql_command_flags[SQLCOM_ANALYZE]=          CF_WRITE_LOGS_COMMAND;
}

/**
  Perform one connection-level (COM_XXXX) command.

  @param command         type of command to perform
  @param session             connection handle
  @param packet          data for the command, packet is always null-terminated
  @param packet_length   length of packet + 1 (to show that data is
                         null-terminated) except for COM_SLEEP, where it
                         can be zero.

  @todo
    set session->lex->sql_command to SQLCOM_END here.
  @todo
    The following has to be changed to an 8 byte integer

  @retval
    0   ok
  @retval
    1   request of thread shutdown, i. e. if command is
        COM_QUIT/COM_SHUTDOWN
*/
bool dispatch_command(enum enum_server_command command, Session *session,
                      char* packet, uint32_t packet_length)
{
  bool error= 0;
  Query_id &query_id= Query_id::get_query_id();

  DRIZZLE_COMMAND_START(session->thread_id,
                        command);

  session->command= command;
  session->lex->sql_command= SQLCOM_END; /* to avoid confusing VIEW detectors */
  session->set_time();
  session->query_id= query_id.value();

  switch( command ) {
  /* Ignore these statements. */
  case COM_PING:
    break;
  /* Increase id and count all other statements. */
  default:
    statistic_increment(session->status_var.questions, &LOCK_status);
    query_id.next();
  }

  /* TODO: set session->lex->sql_command to SQLCOM_END here */

  plugin::Logging::preDo(session);

  session->server_status&=
           ~(SERVER_QUERY_NO_INDEX_USED | SERVER_QUERY_NO_GOOD_INDEX_USED);
  switch (command) {
  case COM_INIT_DB:
  {
    LEX_STRING tmp;
    status_var_increment(session->status_var.com_stat[SQLCOM_CHANGE_DB]);
    tmp.str= packet;
    tmp.length= packet_length;
    if (!mysql_change_db(session, &tmp, false))
    {
      session->my_ok();
    }
    break;
  }
  case COM_QUERY:
  {
    if (! session->readAndStoreQuery(packet, packet_length))
      break;					// fatal error is set
    DRIZZLE_QUERY_START(session->query,
                        session->thread_id,
                        const_cast<const char *>(session->db ? session->db : ""));
    const char* end_of_stmt= NULL;

    mysql_parse(session, session->query, session->query_length, &end_of_stmt);

    break;
  }
  case COM_QUIT:
    /* We don't calculate statistics for this command */
    session->main_da.disable_status();              // Don't send anything back
    error=true;					// End server
    break;
  case COM_SHUTDOWN:
  {
    status_var_increment(session->status_var.com_other);
    session->my_eof();
    session->close_thread_tables();			// Free before kill
    kill_drizzle();
    error=true;
    break;
  }
  case COM_PING:
    status_var_increment(session->status_var.com_other);
    session->my_ok();				// Tell client we are alive
    break;
  case COM_SLEEP:
  case COM_CONNECT:				// Impossible here
  case COM_END:
  default:
    my_message(ER_UNKNOWN_COM_ERROR, ER(ER_UNKNOWN_COM_ERROR), MYF(0));
    break;
  }

  /* If commit fails, we should be able to reset the OK status. */
  session->main_da.can_overwrite_status= true;
  ha_autocommit_or_rollback(session, session->is_error());
  session->main_da.can_overwrite_status= false;

  session->transaction.stmt.reset();


  /* report error issued during command execution */
  if (session->killed_errno())
  {
    if (! session->main_da.is_set())
      session->send_kill_message();
  }
  if (session->killed == Session::KILL_QUERY || session->killed == Session::KILL_BAD_DATA)
  {
    session->killed= Session::NOT_KILLED;
    session->mysys_var->abort= 0;
  }

  /* Can not be true, but do not take chances in production. */
  assert(! session->main_da.is_sent);

  switch (session->main_da.status())
  {
  case Diagnostics_area::DA_ERROR:
    /* The query failed, send error to log and abort bootstrap. */
    session->client->sendError(session->main_da.sql_errno(),
                               session->main_da.message());
    break;

  case Diagnostics_area::DA_EOF:
    session->client->sendEOF();
    break;

  case Diagnostics_area::DA_OK:
    session->client->sendOK();
    break;

  case Diagnostics_area::DA_DISABLED:
    break;

  case Diagnostics_area::DA_EMPTY:
  default:
    session->client->sendOK();
    break;
  }

  session->main_da.is_sent= true;

  session->set_proc_info("closing tables");
  /* Free tables */
  session->close_thread_tables();

  plugin::Logging::postDo(session);

  /* Store temp state for processlist */
  session->set_proc_info("cleaning up");
  session->command= COM_SLEEP;
  memset(session->process_list_info, 0, PROCESS_LIST_WIDTH);
  session->query= 0;
  session->query_length= 0;

  session->set_proc_info(NULL);
  free_root(session->mem_root,MYF(MY_KEEP_PREALLOC));

  if (DRIZZLE_QUERY_DONE_ENABLED() || DRIZZLE_COMMAND_DONE_ENABLED())
  {
    if (command == COM_QUERY)
    {
      DRIZZLE_QUERY_DONE(session->is_error());
    }
    DRIZZLE_COMMAND_DONE(session->is_error());
  }

  return error;
}


/**
  Create a TableList object for an INFORMATION_SCHEMA table.

    This function is used in the parser to convert a SHOW or DESCRIBE
    table_name command to a SELECT from INFORMATION_SCHEMA.
    It prepares a Select_Lex and a TableList object to represent the
    given command as a SELECT parse tree.

  @param session           thread handle
  @param lex               current lex
  @param table_ident       table alias if it's used
  @param schema_table_name the name of the INFORMATION_SCHEMA table to be
                           created

  @note
    Due to the way this function works with memory and LEX it cannot
    be used outside the parser (parse tree transformations outside
    the parser break PS and SP).

  @retval
    0                 success
  @retval
    1                 out of memory or SHOW commands are not allowed
                      in this version of the server.
*/

int prepare_schema_table(Session *session, LEX *lex, Table_ident *table_ident,
                         const string& schema_table_name)
{
  Select_Lex *schema_select_lex= NULL;


  if (schema_table_name.compare("TABLES") == 0 ||
      schema_table_name.compare("TABLE_NAMES") == 0)
  {
    LEX_STRING db;
    size_t dummy;
    if (lex->select_lex.db == NULL &&
        lex->copy_db_to(&lex->select_lex.db, &dummy))
    {
      return (1);
    }
    schema_select_lex= new Select_Lex();
    db.str= schema_select_lex->db= lex->select_lex.db;
    schema_select_lex->table_list.first= NULL;
    db.length= strlen(db.str);

    if (check_db_name(&db))
    {
      my_error(ER_WRONG_DB_NAME, MYF(0), db.str);
      return (1);
    }
  }
  else if (schema_table_name.compare("COLUMNS") == 0 ||
           schema_table_name.compare("STATISTICS") == 0)
  {
    assert(table_ident);
    TableList **query_tables_last= lex->query_tables_last;
    schema_select_lex= new Select_Lex();
    /* 'parent_lex' is used in init_query() so it must be before it. */
    schema_select_lex->parent_lex= lex;
    schema_select_lex->init_query();
    if (! schema_select_lex->add_table_to_list(session, table_ident, 0, 0, TL_READ))
    {
      return (1);
    }
    lex->query_tables_last= query_tables_last;
  }

  Select_Lex *select_lex= lex->current_select;
  assert(select_lex);
  if (make_schema_select(session, select_lex, schema_table_name))
  {
    return(1);
  }
  TableList *table_list= (TableList*) select_lex->table_list.first;
  assert(table_list);
  table_list->schema_select_lex= schema_select_lex;

  return 0;
}

/**
  Execute command saved in session and lex->sql_command.

    Before every operation that can request a write lock for a table
    wait if a global read lock exists. However do not wait if this
    thread has locked tables already. No new locks can be requested
    until the other locks are released. The thread that requests the
    global read lock waits for write locked tables to become unlocked.

    Note that wait_if_global_read_lock() sets a protection against a new
    global read lock when it succeeds. This needs to be released by
    start_waiting_global_read_lock() after the operation.

  @param session                       Thread handle

  @todo
    - Invalidate the table in the query cache if something changed
    after unlocking when changes become visible.
    TODO: this is workaround. right way will be move invalidating in
    the unlock procedure.
    - TODO: use check_change_password()
    - JOIN is not supported yet. TODO
    - SUSPEND and FOR MIGRATE are not supported yet. TODO

  @retval
    false       OK
  @retval
    true        Error
*/

static int
mysql_execute_command(Session *session)
{
  bool res= false;
  LEX  *lex= session->lex;
  /* first Select_Lex (have special meaning for many of non-SELECTcommands) */
  Select_Lex *select_lex= &lex->select_lex;
  /* list of all tables in query */
  TableList *all_tables;
  /* A peek into the query string */
  size_t proc_info_len= session->query_length > PROCESS_LIST_WIDTH ?
                        PROCESS_LIST_WIDTH : session->query_length;

  memcpy(session->process_list_info, session->query, proc_info_len);
  session->process_list_info[proc_info_len]= '\0';

  /*
    In many cases first table of main Select_Lex have special meaning =>
    check that it is first table in global list and relink it first in
    queries_tables list if it is necessary (we need such relinking only
    for queries with subqueries in select list, in this case tables of
    subqueries will go to global list first)

    all_tables will differ from first_table only if most upper Select_Lex
    do not contain tables.

    Because of above in place where should be at least one table in most
    outer Select_Lex we have following check:
    assert(first_table == all_tables);
    assert(first_table == all_tables && first_table != 0);
  */
  lex->first_lists_tables_same();
  /* should be assigned after making first tables same */
  all_tables= lex->query_tables;
  /* set context for commands which do not use setup_tables */
  select_lex->
    context.resolve_in_table_list_only((TableList*)select_lex->
                                       table_list.first);

  /*
    Reset warning count for each query that uses tables
    A better approach would be to reset this for any commands
    that is not a SHOW command or a select that only access local
    variables, but for now this is probably good enough.
    Don't reset warnings when executing a stored routine.
  */
  if (all_tables || ! lex->is_single_level_stmt())
  {
    drizzle_reset_errors(session, 0);
  }

  status_var_increment(session->status_var.com_stat[lex->sql_command]);

  assert(session->transaction.stmt.modified_non_trans_table == false);

  /* now we are ready to execute the statement */
  res= lex->statement->execute();

  session->set_proc_info("query end");

  /*
    The return value for ROW_COUNT() is "implementation dependent" if the
    statement is not DELETE, INSERT or UPDATE, but -1 is what JDBC and ODBC
    wants. We also keep the last value in case of SQLCOM_CALL or
    SQLCOM_EXECUTE.
  */
  if (! (sql_command_flags[lex->sql_command].test(CF_BIT_HAS_ROW_COUNT)))
  {
    session->row_count_func= -1;
  }

  return (res || session->is_error());
}

bool execute_sqlcom_select(Session *session, TableList *all_tables)
{
  LEX	*lex= session->lex;
  select_result *result=lex->result;
  bool res= false;
  /* assign global limit variable if limit is not given */
  {
    Select_Lex *param= lex->unit.global_parameters;
    if (!param->explicit_limit)
      param->select_limit=
        new Item_int((uint64_t) session->variables.select_limit);
  }
  if (!(res= session->openTablesLock(all_tables)))
  {
    if (lex->describe)
    {
      /*
        We always use select_send for EXPLAIN, even if it's an EXPLAIN
        for SELECT ... INTO OUTFILE: a user application should be able
        to prepend EXPLAIN to any query and receive output for it,
        even if the query itself redirects the output.
      */
      if (!(result= new select_send()))
        return true;
      session->send_explain_fields(result);
      res= mysql_explain_union(session, &session->lex->unit, result);
      if (lex->describe & DESCRIBE_EXTENDED)
      {
        char buff[1024];
        String str(buff,(uint32_t) sizeof(buff), system_charset_info);
        str.length(0);
        session->lex->unit.print(&str, QT_ORDINARY);
        str.append('\0');
        push_warning(session, DRIZZLE_ERROR::WARN_LEVEL_NOTE,
                     ER_YES, str.ptr());
      }
      if (res)
        result->abort();
      else
        result->send_eof();
      delete result;
    }
    else
    {
      if (!result && !(result= new select_send()))
        return true;
      res= handle_select(session, lex, result, 0);
      if (result != lex->result)
        delete result;
    }
  }
  return res;
}


#define MY_YACC_INIT 1000			// Start with big alloc
#define MY_YACC_MAX  32000			// Because of 'short'

bool my_yyoverflow(short **yyss, YYSTYPE **yyvs, ulong *yystacksize)
{
  LEX	*lex= current_session->lex;
  ulong old_info=0;
  if ((uint32_t) *yystacksize >= MY_YACC_MAX)
    return 1;
  if (!lex->yacc_yyvs)
    old_info= *yystacksize;
  *yystacksize= set_zone((*yystacksize)*2,MY_YACC_INIT,MY_YACC_MAX);
  unsigned char *tmpptr= NULL;
  if (!(tmpptr= (unsigned char *)realloc(lex->yacc_yyvs,
                                         *yystacksize* sizeof(**yyvs))))
      return 1;
  lex->yacc_yyvs= tmpptr;
  tmpptr= NULL;
  if (!(tmpptr= (unsigned char*)realloc(lex->yacc_yyss,
                                        *yystacksize* sizeof(**yyss))))
      return 1;
  lex->yacc_yyss= tmpptr;
  if (old_info)
  {						// Copy old info from stack
    memcpy(lex->yacc_yyss, *yyss, old_info*sizeof(**yyss));
    memcpy(lex->yacc_yyvs, *yyvs, old_info*sizeof(**yyvs));
  }
  *yyss=(short*) lex->yacc_yyss;
  *yyvs=(YYSTYPE*) lex->yacc_yyvs;
  return 0;
}


void
mysql_init_select(LEX *lex)
{
  Select_Lex *select_lex= lex->current_select;
  select_lex->init_select();
  lex->wild= 0;
  if (select_lex == &lex->select_lex)
  {
    assert(lex->result == 0);
    lex->exchange= 0;
  }
}


bool
mysql_new_select(LEX *lex, bool move_down)
{
  Select_Lex *select_lex;
  Session *session= lex->session;

  if (!(select_lex= new (session->mem_root) Select_Lex()))
    return(1);
  select_lex->select_number= ++session->select_number;
  select_lex->parent_lex= lex; /* Used in init_query. */
  select_lex->init_query();
  select_lex->init_select();
  lex->nest_level++;
  if (lex->nest_level > (int) MAX_SELECT_NESTING)
  {
    my_error(ER_TOO_HIGH_LEVEL_OF_NESTING_FOR_SELECT,MYF(0),MAX_SELECT_NESTING);
    return(1);
  }
  select_lex->nest_level= lex->nest_level;
  if (move_down)
  {
    Select_Lex_Unit *unit;
    /* first select_lex of subselect or derived table */
    if (!(unit= new (session->mem_root) Select_Lex_Unit()))
      return(1);

    unit->init_query();
    unit->init_select();
    unit->session= session;
    unit->include_down(lex->current_select);
    unit->link_next= 0;
    unit->link_prev= 0;
    unit->return_to= lex->current_select;
    select_lex->include_down(unit);
    /*
      By default we assume that it is usual subselect and we have outer name
      resolution context, if no we will assign it to 0 later
    */
    select_lex->context.outer_context= &select_lex->outer_select()->context;
  }
  else
  {
    if (lex->current_select->order_list.first && !lex->current_select->braces)
    {
      my_error(ER_WRONG_USAGE, MYF(0), "UNION", "order_st BY");
      return(1);
    }
    select_lex->include_neighbour(lex->current_select);
    Select_Lex_Unit *unit= select_lex->master_unit();
    if (!unit->fake_select_lex && unit->add_fake_select_lex(lex->session))
      return(1);
    select_lex->context.outer_context=
                unit->first_select()->context.outer_context;
  }

  select_lex->master_unit()->global_parameters= select_lex;
  select_lex->include_global((Select_Lex_Node**)&lex->all_selects_list);
  lex->current_select= select_lex;
  /*
    in subquery is SELECT query and we allow resolution of names in SELECT
    list
  */
  select_lex->context.resolve_in_select_list= true;
  return(0);
}

/**
  Create a select to return the same output as 'SELECT @@var_name'.

  Used for SHOW COUNT(*) [ WARNINGS | ERROR].

  This will crash with a core dump if the variable doesn't exists.

  @param var_name		Variable name
*/

void create_select_for_variable(const char *var_name)
{
  Session *session;
  LEX *lex;
  LEX_STRING tmp, null_lex_string;
  Item *var;
  char buff[MAX_SYS_VAR_LENGTH*2+4+8];
  char *end= buff;

  session= current_session;
  lex= session->lex;
  mysql_init_select(lex);
  lex->sql_command= SQLCOM_SELECT;
  tmp.str= (char*) var_name;
  tmp.length=strlen(var_name);
  memset(&null_lex_string.str, 0, sizeof(null_lex_string));
  /*
    We set the name of Item to @@session.var_name because that then is used
    as the column name in the output.
  */
  if ((var= get_system_var(session, OPT_SESSION, tmp, null_lex_string)))
  {
    end+= sprintf(buff, "@@session.%s", var_name);
    var->set_name(buff, end-buff, system_charset_info);
    session->add_item_to_list(var);
  }
  return;
}


/**
  Parse a query.

  @param       session     Current thread
  @param       inBuf   Begining of the query text
  @param       length  Length of the query text
  @param[out]  found_semicolon For multi queries, position of the character of
                               the next query in the query text.
*/

static void mysql_parse(Session *session, const char *inBuf, uint32_t length,
                 const char ** found_semicolon)
{
  /*
    Warning.
    The purpose of query_cache_send_result_to_client() is to lookup the
    query in the query cache first, to avoid parsing and executing it.
    So, the natural implementation would be to:
    - first, call query_cache_send_result_to_client,
    - second, if caching failed, initialise the lexical and syntactic parser.
    The problem is that the query cache depends on a clean initialization
    of (among others) lex->safe_to_cache_query and session->server_status,
    which are reset respectively in
    - lex_start()
    - mysql_reset_session_for_next_command()
    So, initializing the lexical analyser *before* using the query cache
    is required for the cache to work properly.
    FIXME: cleanup the dependencies in the code to simplify this.
  */
  lex_start(session);
  session->reset_for_next_command();

  {
    LEX *lex= session->lex;

    Lex_input_stream lip(session, inBuf, length);

    bool err= parse_sql(session, &lip);
    *found_semicolon= lip.found_semicolon;

    if (!err)
    {
      {
	if (! session->is_error())
	{
          /*
            Binlog logs a string starting from session->query and having length
            session->query_length; so we set session->query_length correctly (to not
            log several statements in one event, when we executed only first).
            We set it to not see the ';' (otherwise it would get into binlog
            and Query_log_event::print() would give ';;' output).
            This also helps display only the current query in SHOW
            PROCESSLIST.
            Note that we don't need LOCK_thread_count to modify query_length.
          */
          if (*found_semicolon &&
              (session->query_length= (ulong)(*found_semicolon - session->query)))
            session->query_length--;
          DRIZZLE_QUERY_EXEC_START(session->query,
                                   session->thread_id,
                                   const_cast<const char *>(session->db ? session->db : ""));
          /* Actually execute the query */
          mysql_execute_command(session);
          DRIZZLE_QUERY_EXEC_DONE(0);
	}
      }
    }
    else
    {
      assert(session->is_error());
    }
    lex->unit.cleanup();
    session->set_proc_info("freeing items");
    session->end_statement();
    session->cleanup_after_query();
  }

  return;
}



/**
  Store field definition for create.

  @return
    Return 0 if ok
*/

bool add_field_to_list(Session *session, LEX_STRING *field_name, enum_field_types type,
		       char *length, char *decimals,
		       uint32_t type_modifier,
                       enum column_format_type column_format,
		       Item *default_value, Item *on_update_value,
                       LEX_STRING *comment,
		       char *change,
                       List<String> *interval_list, const CHARSET_INFO * const cs)
{
  register CreateField *new_field;
  LEX  *lex= session->lex;
  drizzled::statement::AlterTable *statement= (drizzled::statement::AlterTable *)lex->statement;

  if (check_identifier_name(field_name, ER_TOO_LONG_IDENT))
    return true;

  if (type_modifier & PRI_KEY_FLAG)
  {
    Key *key;
    lex->col_list.push_back(new Key_part_spec(*field_name, 0));
    key= new Key(Key::PRIMARY, null_lex_str,
                      &default_key_create_info,
                      0, lex->col_list);
    statement->alter_info.key_list.push_back(key);
    lex->col_list.empty();
  }
  if (type_modifier & (UNIQUE_FLAG | UNIQUE_KEY_FLAG))
  {
    Key *key;
    lex->col_list.push_back(new Key_part_spec(*field_name, 0));
    key= new Key(Key::UNIQUE, null_lex_str,
                 &default_key_create_info, 0,
                 lex->col_list);
    statement->alter_info.key_list.push_back(key);
    lex->col_list.empty();
  }

  if (default_value)
  {
    /*
      Default value should be literal => basic constants =>
      no need fix_fields()

      We allow only one function as part of default value -
      NOW() as default for TIMESTAMP type.
    */
    if (default_value->type() == Item::FUNC_ITEM &&
        !(((Item_func*)default_value)->functype() == Item_func::NOW_FUNC &&
         type == DRIZZLE_TYPE_TIMESTAMP))
    {
      my_error(ER_INVALID_DEFAULT, MYF(0), field_name->str);
      return true;
    }
    else if (default_value->type() == Item::NULL_ITEM)
    {
      default_value= 0;
      if ((type_modifier & (NOT_NULL_FLAG | AUTO_INCREMENT_FLAG)) ==
	  NOT_NULL_FLAG)
      {
	my_error(ER_INVALID_DEFAULT, MYF(0), field_name->str);
	return true;
      }
    }
    else if (type_modifier & AUTO_INCREMENT_FLAG)
    {
      my_error(ER_INVALID_DEFAULT, MYF(0), field_name->str);
      return true;
    }
  }

  if (on_update_value && type != DRIZZLE_TYPE_TIMESTAMP)
  {
    my_error(ER_INVALID_ON_UPDATE, MYF(0), field_name->str);
    return true;
  }

  if (!(new_field= new CreateField()) ||
      new_field->init(session, field_name->str, type, length, decimals, type_modifier,
                      default_value, on_update_value, comment, change,
                      interval_list, cs, 0, column_format))
    return true;

  statement->alter_info.create_list.push_back(new_field);
  lex->last_field=new_field;

  return false;
}


/** Store position for column in ALTER TABLE .. ADD column. */

void store_position_for_column(const char *name)
{
  current_session->lex->last_field->after=const_cast<char*> (name);
}

/**
  Add a table to list of used tables.

  @param table		Table to add
  @param alias		alias for table (or null if no alias)
  @param table_options	A set of the following bits:
                         - TL_OPTION_UPDATING : Table will be updated
                         - TL_OPTION_FORCE_INDEX : Force usage of index
                         - TL_OPTION_ALIAS : an alias in multi table DELETE
  @param lock_type	How table should be locked
  @param use_index	List of indexed used in USE INDEX
  @param ignore_index	List of indexed used in IGNORE INDEX

  @retval
      0		Error
  @retval
    \#	Pointer to TableList element added to the total table list
*/

TableList *Select_Lex::add_table_to_list(Session *session,
					     Table_ident *table,
					     LEX_STRING *alias,
					     uint32_t table_options,
					     thr_lock_type lock_type,
					     List<Index_hint> *index_hints_arg,
                                             LEX_STRING *option)
{
  register TableList *ptr;
  TableList *previous_table_ref; /* The table preceding the current one. */
  char *alias_str;
  LEX *lex= session->lex;

  if (!table)
    return NULL;				// End of memory
  alias_str= alias ? alias->str : table->table.str;
  if (!test(table_options & TL_OPTION_ALIAS) &&
      check_table_name(table->table.str, table->table.length))
  {
    my_error(ER_WRONG_TABLE_NAME, MYF(0), table->table.str);
    return NULL;
  }

  if (table->is_derived_table() == false && table->db.str &&
      check_db_name(&table->db))
  {
    my_error(ER_WRONG_DB_NAME, MYF(0), table->db.str);
    return NULL;
  }

  if (!alias)					/* Alias is case sensitive */
  {
    if (table->sel)
    {
      my_message(ER_DERIVED_MUST_HAVE_ALIAS,
                 ER(ER_DERIVED_MUST_HAVE_ALIAS), MYF(0));
      return NULL;
    }
    if (!(alias_str= (char*) session->memdup(alias_str,table->table.length+1)))
      return NULL;
  }
  if (!(ptr = (TableList *) session->calloc(sizeof(TableList))))
    return NULL;
  if (table->db.str)
  {
    ptr->is_fqtn= true;
    ptr->db= table->db.str;
    ptr->db_length= table->db.length;
  }
  else if (lex->copy_db_to(&ptr->db, &ptr->db_length))
    return NULL;
  else
    ptr->is_fqtn= false;

  ptr->alias= alias_str;
  ptr->is_alias= alias ? true : false;
  if (table->table.length)
    table->table.length= my_casedn_str(files_charset_info, table->table.str);
  ptr->table_name=table->table.str;
  ptr->table_name_length=table->table.length;
  ptr->lock_type=   lock_type;
  ptr->updating=    test(table_options & TL_OPTION_UPDATING);
  ptr->force_index= test(table_options & TL_OPTION_FORCE_INDEX);
  ptr->ignore_leaves= test(table_options & TL_OPTION_IGNORE_LEAVES);
  ptr->derived=	    table->sel;
  if (!ptr->derived && !my_strcasecmp(system_charset_info, ptr->db,
                                      INFORMATION_SCHEMA_NAME.c_str()))
  {
    plugin::InfoSchemaTable *schema_table= plugin::InfoSchemaTable::getTable(ptr->table_name);
    if (!schema_table ||
        (schema_table->isHidden() &&
         ((sql_command_flags[lex->sql_command].test(CF_BIT_STATUS_COMMAND)) == 0 ||
          /*
            this check is used for show columns|keys from I_S hidden table
          */
          lex->sql_command == SQLCOM_SHOW_FIELDS ||
          lex->sql_command == SQLCOM_SHOW_KEYS)))
    {
      my_error(ER_UNKNOWN_TABLE, MYF(0),
               ptr->table_name, INFORMATION_SCHEMA_NAME.c_str());
      return NULL;
    }
  }
  ptr->select_lex=  lex->current_select;
  ptr->index_hints= index_hints_arg;
  ptr->option= option ? option->str : 0;
  /* check that used name is unique */
  if (lock_type != TL_IGNORE)
  {
    TableList *first_table= (TableList*) table_list.first;
    for (TableList *tables= first_table ;
	 tables ;
	 tables=tables->next_local)
    {
      if (!my_strcasecmp(table_alias_charset, alias_str, tables->alias) &&
	  !strcmp(ptr->db, tables->db))
      {
	my_error(ER_NONUNIQ_TABLE, MYF(0), alias_str);
	return NULL;
      }
    }
  }
  /* Store the table reference preceding the current one. */
  if (table_list.elements > 0)
  {
    /*
      table_list.next points to the last inserted TableList->next_local'
      element
      We don't use the offsetof() macro here to avoid warnings from gcc
    */
    previous_table_ref= (TableList*) ((char*) table_list.next -
                                       ((char*) &(ptr->next_local) -
                                        (char*) ptr));
    /*
      Set next_name_resolution_table of the previous table reference to point
      to the current table reference. In effect the list
      TableList::next_name_resolution_table coincides with
      TableList::next_local. Later this may be changed in
      store_top_level_join_columns() for NATURAL/USING joins.
    */
    previous_table_ref->next_name_resolution_table= ptr;
  }

  /*
    Link the current table reference in a local list (list for current select).
    Notice that as a side effect here we set the next_local field of the
    previous table reference to 'ptr'. Here we also add one element to the
    list 'table_list'.
  */
  table_list.link_in_list((unsigned char*) ptr, (unsigned char**) &ptr->next_local);
  ptr->next_name_resolution_table= NULL;
  /* Link table in global list (all used tables) */
  lex->add_to_query_tables(ptr);
  return ptr;
}


/**
  Initialize a new table list for a nested join.

    The function initializes a structure of the TableList type
    for a nested join. It sets up its nested join list as empty.
    The created structure is added to the front of the current
    join list in the Select_Lex object. Then the function
    changes the current nest level for joins to refer to the newly
    created empty list after having saved the info on the old level
    in the initialized structure.

  @param session         current thread

  @retval
    0   if success
  @retval
    1   otherwise
*/

bool Select_Lex::init_nested_join(Session *session)
{
  TableList *ptr;
  nested_join_st *nested_join;

  if (!(ptr= (TableList*) session->calloc(ALIGN_SIZE(sizeof(TableList))+
                                       sizeof(nested_join_st))))
    return true;
  nested_join= ptr->nested_join=
    ((nested_join_st*) ((unsigned char*) ptr + ALIGN_SIZE(sizeof(TableList))));

  join_list->push_front(ptr);
  ptr->embedding= embedding;
  ptr->join_list= join_list;
  ptr->alias= (char*) "(nested_join)";
  embedding= ptr;
  join_list= &nested_join->join_list;
  join_list->empty();
  return false;
}


/**
  End a nested join table list.

    The function returns to the previous join nest level.
    If the current level contains only one member, the function
    moves it one level up, eliminating the nest.

  @param session         current thread

  @return
    - Pointer to TableList element added to the total table list, if success
    - 0, otherwise
*/

TableList *Select_Lex::end_nested_join(Session *)
{
  TableList *ptr;
  nested_join_st *nested_join;

  assert(embedding);
  ptr= embedding;
  join_list= ptr->join_list;
  embedding= ptr->embedding;
  nested_join= ptr->nested_join;
  if (nested_join->join_list.elements == 1)
  {
    TableList *embedded= nested_join->join_list.head();
    join_list->pop();
    embedded->join_list= join_list;
    embedded->embedding= embedding;
    join_list->push_front(embedded);
    ptr= embedded;
  }
  else if (nested_join->join_list.elements == 0)
  {
    join_list->pop();
    ptr= NULL;                                     // return value
  }
  return ptr;
}


/**
  Nest last join operation.

    The function nest last join operation as if it was enclosed in braces.

  @param session         current thread

  @retval
    0  Error
  @retval
    \#  Pointer to TableList element created for the new nested join
*/

TableList *Select_Lex::nest_last_join(Session *session)
{
  TableList *ptr;
  nested_join_st *nested_join;
  List<TableList> *embedded_list;

  if (!(ptr= (TableList*) session->calloc(ALIGN_SIZE(sizeof(TableList))+
                                       sizeof(nested_join_st))))
    return NULL;
  nested_join= ptr->nested_join=
    ((nested_join_st*) ((unsigned char*) ptr + ALIGN_SIZE(sizeof(TableList))));

  ptr->embedding= embedding;
  ptr->join_list= join_list;
  ptr->alias= (char*) "(nest_last_join)";
  embedded_list= &nested_join->join_list;
  embedded_list->empty();

  for (uint32_t i=0; i < 2; i++)
  {
    TableList *table= join_list->pop();
    table->join_list= embedded_list;
    table->embedding= ptr;
    embedded_list->push_back(table);
    if (table->natural_join)
    {
      ptr->is_natural_join= true;
      /*
        If this is a JOIN ... USING, move the list of joined fields to the
        table reference that describes the join.
      */
      if (prev_join_using)
        ptr->join_using_fields= prev_join_using;
    }
  }
  join_list->push_front(ptr);
  nested_join->used_tables= nested_join->not_null_tables= (table_map) 0;
  return ptr;
}


/**
  Add a table to the current join list.

    The function puts a table in front of the current join list
    of Select_Lex object.
    Thus, joined tables are put into this list in the reverse order
    (the most outer join operation follows first).

  @param table       the table to add

  @return
    None
*/

void Select_Lex::add_joined_table(TableList *table)
{
  join_list->push_front(table);
  table->join_list= join_list;
  table->embedding= embedding;
}


/**
  Convert a right join into equivalent left join.

    The function takes the current join list t[0],t[1] ... and
    effectively converts it into the list t[1],t[0] ...
    Although the outer_join flag for the new nested table contains
    JOIN_TYPE_RIGHT, it will be handled as the inner table of a left join
    operation.

  EXAMPLES
  @verbatim
    SELECT * FROM t1 RIGHT JOIN t2 ON on_expr =>
      SELECT * FROM t2 LEFT JOIN t1 ON on_expr

    SELECT * FROM t1,t2 RIGHT JOIN t3 ON on_expr =>
      SELECT * FROM t1,t3 LEFT JOIN t2 ON on_expr

    SELECT * FROM t1,t2 RIGHT JOIN (t3,t4) ON on_expr =>
      SELECT * FROM t1,(t3,t4) LEFT JOIN t2 ON on_expr

    SELECT * FROM t1 LEFT JOIN t2 ON on_expr1 RIGHT JOIN t3  ON on_expr2 =>
      SELECT * FROM t3 LEFT JOIN (t1 LEFT JOIN t2 ON on_expr2) ON on_expr1
   @endverbatim

  @param session         current thread

  @return
    - Pointer to the table representing the inner table, if success
    - 0, otherwise
*/

TableList *Select_Lex::convert_right_join()
{
  TableList *tab2= join_list->pop();
  TableList *tab1= join_list->pop();

  join_list->push_front(tab2);
  join_list->push_front(tab1);
  tab1->outer_join|= JOIN_TYPE_RIGHT;

  return tab1;
}

/**
  Set lock for all tables in current select level.

  @param lock_type			Lock to set for tables

  @note
    If lock is a write lock, then tables->updating is set 1
    This is to get tables_ok to know that the table is updated by the
    query
*/

void Select_Lex::set_lock_for_tables(thr_lock_type lock_type)
{
  bool for_update= lock_type >= TL_READ_NO_INSERT;

  for (TableList *tables= (TableList*) table_list.first;
       tables;
       tables= tables->next_local)
  {
    tables->lock_type= lock_type;
    tables->updating=  for_update;
  }
  return;
}


/**
  Create a fake Select_Lex for a unit.

    The method create a fake Select_Lex object for a unit.
    This object is created for any union construct containing a union
    operation and also for any single select union construct of the form
    @verbatim
    (SELECT ... order_st BY order_list [LIMIT n]) order_st BY ...
    @endvarbatim
    or of the form
    @varbatim
    (SELECT ... order_st BY LIMIT n) order_st BY ...
    @endvarbatim

  @param session_arg		   thread handle

  @note
    The object is used to retrieve rows from the temporary table
    where the result on the union is obtained.

  @retval
    1     on failure to create the object
  @retval
    0     on success
*/

bool Select_Lex_Unit::add_fake_select_lex(Session *session_arg)
{
  Select_Lex *first_sl= first_select();
  assert(!fake_select_lex);

  if (!(fake_select_lex= new (session_arg->mem_root) Select_Lex()))
      return(1);
  fake_select_lex->include_standalone(this,
                                      (Select_Lex_Node**)&fake_select_lex);
  fake_select_lex->select_number= INT_MAX;
  fake_select_lex->parent_lex= session_arg->lex; /* Used in init_query. */
  fake_select_lex->make_empty_select();
  fake_select_lex->linkage= GLOBAL_OPTIONS_TYPE;
  fake_select_lex->select_limit= 0;

  fake_select_lex->context.outer_context=first_sl->context.outer_context;
  /* allow item list resolving in fake select for order_st BY */
  fake_select_lex->context.resolve_in_select_list= true;
  fake_select_lex->context.select_lex= fake_select_lex;

  if (!is_union())
  {
    /*
      This works only for
      (SELECT ... order_st BY list [LIMIT n]) order_st BY order_list [LIMIT m],
      (SELECT ... LIMIT n) order_st BY order_list [LIMIT m]
      just before the parser starts processing order_list
    */
    global_parameters= fake_select_lex;
    fake_select_lex->no_table_names_allowed= 1;
    session_arg->lex->current_select= fake_select_lex;
  }
  session_arg->lex->pop_context();
  return(0);
}


/**
  Push a new name resolution context for a JOIN ... ON clause to the
  context stack of a query block.

    Create a new name resolution context for a JOIN ... ON clause,
    set the first and last leaves of the list of table references
    to be used for name resolution, and push the newly created
    context to the stack of contexts of the query.

  @param session       pointer to current thread
  @param left_op   left  operand of the JOIN
  @param right_op  rigth operand of the JOIN

  @retval
    false  if all is OK
  @retval
    true   if a memory allocation error occured
*/

bool
push_new_name_resolution_context(Session *session,
                                 TableList *left_op, TableList *right_op)
{
  Name_resolution_context *on_context;
  if (!(on_context= new (session->mem_root) Name_resolution_context))
    return true;
  on_context->init();
  on_context->first_name_resolution_table=
    left_op->first_leaf_for_name_resolution();
  on_context->last_name_resolution_table=
    right_op->last_leaf_for_name_resolution();
  return session->lex->push_context(on_context);
}


/**
  Add an ON condition to the second operand of a JOIN ... ON.

    Add an ON condition to the right operand of a JOIN ... ON clause.

  @param b     the second operand of a JOIN ... ON
  @param expr  the condition to be added to the ON clause

  @retval
    false  if there was some error
  @retval
    true   if all is OK
*/

void add_join_on(TableList *b, Item *expr)
{
  if (expr)
  {
    if (!b->on_expr)
      b->on_expr= expr;
    else
    {
      /*
        If called from the parser, this happens if you have both a
        right and left join. If called later, it happens if we add more
        than one condition to the ON clause.
      */
      b->on_expr= new Item_cond_and(b->on_expr,expr);
    }
    b->on_expr->top_level_item();
  }
}


/**
  Mark that there is a NATURAL JOIN or JOIN ... USING between two
  tables.

    This function marks that table b should be joined with a either via
    a NATURAL JOIN or via JOIN ... USING. Both join types are special
    cases of each other, so we treat them together. The function
    setup_conds() creates a list of equal condition between all fields
    of the same name for NATURAL JOIN or the fields in 'using_fields'
    for JOIN ... USING. The list of equality conditions is stored
    either in b->on_expr, or in JOIN::conds, depending on whether there
    was an outer join.

  EXAMPLE
  @verbatim
    SELECT * FROM t1 NATURAL LEFT JOIN t2
     <=>
    SELECT * FROM t1 LEFT JOIN t2 ON (t1.i=t2.i and t1.j=t2.j ... )

    SELECT * FROM t1 NATURAL JOIN t2 WHERE <some_cond>
     <=>
    SELECT * FROM t1, t2 WHERE (t1.i=t2.i and t1.j=t2.j and <some_cond>)

    SELECT * FROM t1 JOIN t2 USING(j) WHERE <some_cond>
     <=>
    SELECT * FROM t1, t2 WHERE (t1.j=t2.j and <some_cond>)
   @endverbatim

  @param a		  Left join argument
  @param b		  Right join argument
  @param using_fields    Field names from USING clause
*/

void add_join_natural(TableList *a, TableList *b, List<String> *using_fields,
                      Select_Lex *lex)
{
  b->natural_join= a;
  lex->prev_join_using= using_fields;
}


/**
  kill on thread.

  @param session			Thread class
  @param id			Thread id
  @param only_kill_query        Should it kill the query or the connection

  @note
    This is written such that we have a short lock on LOCK_thread_count
*/

static unsigned int
kill_one_thread(Session *, ulong id, bool only_kill_query)
{
  Session *tmp= NULL;
  uint32_t error=ER_NO_SUCH_THREAD;
  pthread_mutex_lock(&LOCK_thread_count); // For unlink from list
  
  for( vector<Session*>::iterator it= session_list.begin(); it != session_list.end(); ++it )
  {
    if ((*it)->thread_id == id)
    {
      tmp= *it;
      pthread_mutex_lock(&tmp->LOCK_delete);	// Lock from delete
      break;
    }
  }
  pthread_mutex_unlock(&LOCK_thread_count);
  if (tmp)
  {
    tmp->awake(only_kill_query ? Session::KILL_QUERY : Session::KILL_CONNECTION);
    error=0;
    pthread_mutex_unlock(&tmp->LOCK_delete);
  }
  return(error);
}


/*
  kills a thread and sends response

  SYNOPSIS
    sql_kill()
    session			Thread class
    id			Thread id
    only_kill_query     Should it kill the query or the connection
*/

void sql_kill(Session *session, ulong id, bool only_kill_query)
{
  uint32_t error;
  if (!(error= kill_one_thread(session, id, only_kill_query)))
    session->my_ok();
  else
    my_error(error, MYF(0), id);
}


/**
  Check if the select is a simple select (not an union).

  @retval
    0	ok
  @retval
    1	error	; In this case the error messege is sent to the client
*/

bool check_simple_select()
{
  Session *session= current_session;
  LEX *lex= session->lex;
  if (lex->current_select != &lex->select_lex)
  {
    char command[80];
    Lex_input_stream *lip= session->m_lip;
    strncpy(command, lip->yylval->symbol.str,
            min(lip->yylval->symbol.length, (uint32_t)(sizeof(command)-1)));
    command[min(lip->yylval->symbol.length, (uint32_t)(sizeof(command)-1))]=0;
    my_error(ER_CANT_USE_OPTION_HERE, MYF(0), command);
    return 1;
  }
  return 0;
}


/**
  Construct ALL/ANY/SOME subquery Item.

  @param left_expr   pointer to left expression
  @param cmp         compare function creator
  @param all         true if we create ALL subquery
  @param select_lex  pointer on parsed subquery structure

  @return
    constructed Item (or 0 if out of memory)
*/
Item * all_any_subquery_creator(Item *left_expr,
                                chooser_compare_func_creator cmp,
                                bool all,
                                Select_Lex *select_lex)
{
  if ((cmp == &comp_eq_creator) && !all)       //  = ANY <=> IN
    return new Item_in_subselect(left_expr, select_lex);

  if ((cmp == &comp_ne_creator) && all)        // <> ALL <=> NOT IN
    return new Item_func_not(new Item_in_subselect(left_expr, select_lex));

  Item_allany_subselect *it=
    new Item_allany_subselect(left_expr, cmp, select_lex, all);
  if (all)
    return it->upper_item= new Item_func_not_all(it);	/* ALL */

  return it->upper_item= new Item_func_nop_all(it);      /* ANY/SOME */
}


/**
  Update query pre-check.

  @param session		Thread handler
  @param tables	Global/local table list (have to be the same)

  @retval
    false OK
  @retval
    true  Error
*/

bool update_precheck(Session *session, TableList *)
{
  const char *msg= 0;
  LEX *lex= session->lex;
  Select_Lex *select_lex= &lex->select_lex;

  if (session->lex->select_lex.item_list.elements != session->lex->value_list.elements)
  {
    my_message(ER_WRONG_VALUE_COUNT, ER(ER_WRONG_VALUE_COUNT), MYF(0));
    return(true);
  }

  if (session->lex->select_lex.table_list.elements > 1)
  {
    if (select_lex->order_list.elements)
      msg= "ORDER BY";
    else if (select_lex->select_limit)
      msg= "LIMIT";
    if (msg)
    {
      my_error(ER_WRONG_USAGE, MYF(0), "UPDATE", msg);
      return(true);
    }
  }
  return(false);
}


/**
  simple INSERT query pre-check.

  @param session		Thread handler
  @param tables	Global table list

  @retval
    false  OK
  @retval
    true   error
*/

bool insert_precheck(Session *session, TableList *)
{
  LEX *lex= session->lex;

  /*
    Check that we have modify privileges for the first table and
    select privileges for the rest
  */
  if (lex->update_list.elements != lex->value_list.elements)
  {
    my_message(ER_WRONG_VALUE_COUNT, ER(ER_WRONG_VALUE_COUNT), MYF(0));
    return(true);
  }
  return(false);
}


/**
  CREATE TABLE query pre-check.

  @param session			Thread handler
  @param tables		Global table list
  @param create_table	        Table which will be created

  @retval
    false   OK
  @retval
    true   Error
*/

bool create_table_precheck(TableIdentifier &identifier)
{
  if (strcmp(identifier.getDBName(), "information_schema") == 0)
  {
    my_error(ER_DBACCESS_DENIED_ERROR, MYF(0), "", "", INFORMATION_SCHEMA_NAME.c_str());
    return true;
  }

  return false;
}


/**
  negate given expression.

  @param session  thread handler
  @param expr expression for negation

  @return
    negated expression
*/

Item *negate_expression(Session *session, Item *expr)
{
  Item *negated;
  if (expr->type() == Item::FUNC_ITEM &&
      ((Item_func *) expr)->functype() == Item_func::NOT_FUNC)
  {
    /* it is NOT(NOT( ... )) */
    Item *arg= ((Item_func *) expr)->arguments()[0];
    enum_parsing_place place= session->lex->current_select->parsing_place;
    if (arg->is_bool_func() || place == IN_WHERE || place == IN_HAVING)
      return arg;
    /*
      if it is not boolean function then we have to emulate value of
      not(not(a)), it will be a != 0
    */
    return new Item_func_ne(arg, new Item_int((char*) "0", 0, 1));
  }

  if ((negated= expr->neg_transformer(session)) != 0)
    return negated;
  return new Item_func_not(expr);
}


/*
  Check that char length of a string does not exceed some limit.

  SYNOPSIS
  check_string_char_length()
      str              string to be checked
      err_msg          error message to be displayed if the string is too long
      max_char_length  max length in symbols
      cs               string charset

  RETURN
    false   the passed string is not longer than max_char_length
    true    the passed string is longer than max_char_length
*/


bool check_string_char_length(LEX_STRING *str, const char *err_msg,
                              uint32_t max_char_length, const CHARSET_INFO * const cs,
                              bool no_error)
{
  int well_formed_error;
  uint32_t res= cs->cset->well_formed_len(cs, str->str, str->str + str->length,
                                      max_char_length, &well_formed_error);

  if (!well_formed_error &&  str->length == res)
    return false;

  if (!no_error)
    my_error(ER_WRONG_STRING_LENGTH, MYF(0), str->str, err_msg, max_char_length);
  return true;
}


bool check_identifier_name(LEX_STRING *str, uint32_t err_code,
                           uint32_t max_char_length,
                           const char *param_for_err_msg)
{
  /*
    We don't support non-BMP characters in identifiers at the moment,
    so they should be prohibited until such support is done.
    This is why we use the 3-byte utf8 to check well-formedness here.
  */
  const CHARSET_INFO * const cs= &my_charset_utf8mb4_general_ci;

  int well_formed_error;
  uint32_t res= cs->cset->well_formed_len(cs, str->str, str->str + str->length,
                                      max_char_length, &well_formed_error);

  if (well_formed_error)
  {
    my_error(ER_INVALID_CHARACTER_STRING, MYF(0), "identifier", str->str);
    return true;
  }

  if (str->length == res)
    return false;

  switch (err_code)
  {
  case 0:
    break;
  case ER_WRONG_STRING_LENGTH:
    my_error(err_code, MYF(0), str->str, param_for_err_msg, max_char_length);
    break;
  case ER_TOO_LONG_IDENT:
    my_error(err_code, MYF(0), str->str);
    break;
  default:
    assert(0);
    break;
  }
  return true;
}

extern int DRIZZLEparse(void *session); // from sql_yacc.cc


/**
  This is a wrapper of DRIZZLEparse(). All the code should call parse_sql()
  instead of DRIZZLEparse().

  @param session Thread context.
  @param lip Lexer context.

  @return Error status.
    @retval false on success.
    @retval true on parsing error.
*/

static bool parse_sql(Session *session, Lex_input_stream *lip)
{
  assert(session->m_lip == NULL);

  DRIZZLE_QUERY_PARSE_START(session->query);

  /* Set Lex_input_stream. */

  session->m_lip= lip;

  /* Parse the query. */

  bool mysql_parse_status= DRIZZLEparse(session) != 0;

  /* Check that if DRIZZLEparse() failed, session->is_error() is set. */

  assert(!mysql_parse_status || session->is_error());

  /* Reset Lex_input_stream. */

  session->m_lip= NULL;

  DRIZZLE_QUERY_PARSE_DONE(mysql_parse_status || session->is_fatal_error);

  /* That's it. */

  return mysql_parse_status || session->is_fatal_error;
}

/**
  @} (end of group Runtime_Environment)
*/
1 by brian clean slate	1	/* Copyright (C) 2000-2003 MySQL AB
	2
	3	This program is free software; you can redistribute it and/or modify
	4	it under the terms of the GNU General Public License as published by
	5	the Free Software Foundation; version 2 of the License.
	6
	7	This program is distributed in the hope that it will be useful,
	8	but WITHOUT ANY WARRANTY; without even the implied warranty of
	9	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	10	GNU General Public License for more details.
	11
	12	You should have received a copy of the GNU General Public License
	13	along with this program; if not, write to the Free Software
	14	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
	15
319.1.1 by Grant Limberg renamed all instances of MYSQL_ to DRIZZLE_	16	#define DRIZZLE_LEX 1
243.1.17 by Jay Pipes FINAL PHASE removal of mysql_priv.h (Bye, bye my friend.)	17	#include <drizzled/server_includes.h>
614 by Brian Aker Remove filtering (wrong layer, belongs in plugin).	18	#include <mysys/hash.h>
575.4.6 by Monty Taylor Removed my_getwd.	19	#include <drizzled/db.h>
549 by Monty Taylor Took gettext.h out of header files.	20	#include <drizzled/error.h>
553.1.3 by Monty Taylor Split out nested_join.h.	21	#include <drizzled/nested_join.h>
561.1.3 by Monty Taylor Split some more things out of common_includes.h.	22	#include <drizzled/query_id.h>
520.8.2 by Monty Taylor Moved sql_parse.h and sql_error.h out of common_includes.	23	#include <drizzled/sql_parse.h>
520.6.7 by Monty Taylor Moved a bunch of crap out of common_includes.	24	#include <drizzled/data_home.h>
575.4.7 by Monty Taylor More header cleanup.	25	#include <drizzled/sql_base.h>
575.4.7 by Monty Taylor More header cleanup.	26	#include <drizzled/show.h>
1130.1.7 by Monty Taylor Renamed plugin::InfoSchema to plugin::InfoSchemaTable as per Jay.	27	#include <drizzled/plugin/info_schema_table.h>
670.1.20 by Monty Taylor Renamed functions to function... everything else is singular.	28	#include <drizzled/function/time/unix_timestamp.h>
	29	#include <drizzled/function/get_system_var.h>
584.4.7 by Monty Taylor Removed a big bank of includes from item.h.	30	#include <drizzled/item/cmpfunc.h>
642.1.20 by Lee header file clean up	31	#include <drizzled/item/null.h>
584.1.15 by Monty Taylor The mega-patch from hell. Renamed sql_class to session (since that's what it is) and removed it and field and table from common_includes.	32	#include <drizzled/session.h>
	33	#include <drizzled/sql_load.h>
670.2.4 by Monty Taylor Removed more stuff from the headers.	34	#include <drizzled/lock.h>
837 by Brian Aker Reworked some classes out of session.h	35	#include <drizzled/select_send.h>
971.6.1 by Eric Day Renamed Protocol to Client, cleaned up some unnecessary methods along the way.	36	#include <drizzled/plugin/client.h>
1100.3.30 by Padraig O'Sullivan Renamed the Command class to be Statement. Renamed the command directory to	37	#include <drizzled/statement.h>
1128.2.4 by Brian Aker AlterInfo refactor back to class.	38	#include <drizzled/statement/alter_table.h>
1126.10.18 by Padraig O'Sullivan Various small build fixes for when dtrace is enabled.	39	#include "drizzled/probes.h"
1100.3.1 by Padraig O'Sullivan Beginnings of reworking the mysql_execute_command() method.	40