~drizzle-trunk/drizzle/development

# ==== Purpose ====

#

# Check if the two given tables (possibly residing on different

# master/slave servers) are equal.

#

# ==== Usage ====

#

# The tables to check are given by the test language variables

# $diff_table_1 and $diff_table_2.  They must be of the

# following form:

#

#  [master:|slave:]database.table

#

# I.e., both database and table must be speicified.  Optionally, you

# can prefix the name with 'master:' (to read the table on master) or

# with 'slave:' (to read the table on slave).  If no prefix is given,

# reads the table from the current connection.  If one of these

# variables has a prefix, both should have a prefix.

#

# ==== Side effects ====

#

# - Prints "Comparing tables $diff_table_1 and $diff_tables_2".

#

# - If the tables are different, prints the difference in a

#   system-specific format (unified diff if supported) and generates

#   an error.

#

# - If $diff_table_1 or $diff_table_2 begins with 'master:' or

#   'slave:', it will stay connected to one of those hosts after

#   execution.  The host is only guaranteed to remain unchanged if

#   none of $diff_table_1 or $diff_table_2 begins with 'master:' or

#   'slave:'.

#

# ==== Bugs ====

#

# - It is currently not possible to use this for tables that are

#   supposed to be different, because if the files are different:

#    - 'diff' produces system-dependent output,

#    - the output includes the absolute path of the compared files,

#    - the output includes a timestamp.

#   To fix that, we'd probably have to use SQL to compute the

#   symmetric difference between the tables.  I'm not sure how to do

#   that efficiently.  If we implement this, it would be nice to

#   compare the table definitions too.

#

# - It actually compares the result of "SELECT * FROM table ORDER BY

#   col1, col2, ..., colN INTO OUTFILE 'file'".  Hence, it is assumed

#   that the comparison orders for both tables are equal and that two

#   rows that are equal in the comparison order cannot differ, e.g.,

#   by character case.

# ==== Save both tables to file ====

--echo Comparing tables $diff_table_1 and $diff_table_2

disable_query_log;

--error 0,1

--remove_file $MYSQLTEST_VARDIR/tmp/diff_table_1

--error 0,1

--remove_file $MYSQLTEST_VARDIR/tmp/diff_table_2

let $_diff_table=$diff_table_2;

let $_diff_i=2;

while ($_diff_i) {

  # Parse out any leading "master:" or "slave:" from the table

  # specification and connect the appropriate server.

  let $_diff_conn_master=`SELECT SUBSTR('$_diff_table', 1, 7) = 'master:'`;

  if ($_diff_conn_master) {

    let $_diff_table=`SELECT SUBSTR('$_diff_table', 8)`;

    connection master;

  }

  let $_diff_conn_slave=`SELECT SUBSTR('$_diff_table', 1, 6) = 'slave:'`;

  if ($_diff_conn_slave) {

    let $_diff_table=`SELECT SUBSTR('$_diff_table', 7)`;

    connection slave;

  }

  # Sanity-check the input.

  let $_diff_error= `SELECT '$_diff_table' NOT LIKE '_%._%'`;

  if ($_diff_error) {

    --echo !!!ERROR IN TEST: \$diff_table_$_diff_i='$_diff_table' is not in the form database.table

    exit;

  }

  # We need the output files to be sorted (so that diff_files does not

  # think the files are different just because they are differently

  # ordered).  To this end, we first generate a query that sorts the

  # table by all columns.  Since ORDER BY accept column indices, we

  # just generate a comma-separated list of all numbers from 1 to the

  # number of columns in the table.

  let $_diff_column_index=`SELECT MAX(ordinal_position)

                           FROM information_schema.columns

                           WHERE CONCAT(table_schema, '.', table_name) =

                                 '$_diff_table'`;

  let $_diff_column_list=$_diff_column_index;

  dec $_diff_column_index;

  while ($_diff_column_index) {

    let $_diff_column_list=$_diff_column_index, $_diff_column_list;

    dec $_diff_column_index;

  }

  # Now that we have the comma-separated list of columns, we can write

  # the table to a file.

  eval SELECT * FROM $_diff_table ORDER BY $_diff_column_list

              INTO OUTFILE '$MYSQLTEST_VARDIR/tmp/diff_table_$_diff_i';

  # Do the same for $diff_table_1.

  dec $_diff_i;

  let $_diff_table=$diff_table_1;

}

# ==== Compare the generated files ====

diff_files $MYSQLTEST_VARDIR/tmp/diff_table_1 $MYSQLTEST_VARDIR/tmp/diff_table_2;

--remove_file $MYSQLTEST_VARDIR/tmp/diff_table_1

--remove_file $MYSQLTEST_VARDIR/tmp/diff_table_2

enable_query_log;