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=================
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[Warning: this description is work in progress and may be incomplete]
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The table record is stored in a fixed-size buffer:
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record: null_bytes, column1_data, column2_data, ...
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The offsets of the parts of the buffer are also fixed: every column has
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The offsets of the parts of the buffer are also fixed: every column has
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an offset to its column{i}_data, and if it is nullable it also has its own
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The record buffer only includes data about columns that are marked in the
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relevant column set (table->read_set and/or table->write_set, depending on
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<not-sure>It could be that it is required that null bits of non-present
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columns are set to 1</not-sure>
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VARIOUS EXCEPTIONS AND SPECIAL CASES
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f the table has no nullable columns, then null_bytes is still
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present, its length is one byte <not-sure> which must be set to 0xFF
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f the table has no nullable columns, then null_bytes is still
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present, its length is one byte <not-sure> which must be set to 0xFF
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at all times. </not-sure>
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If the table has columns of type BIT, then certain bits from those columns
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may be stored in null_bytes as well. Grep around for Field_bit for
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For blob columns (see Field_blob), the record buffer stores length of the
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data, following by memory pointer to the blob data. The pointer is owned
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For blob columns (see Field_blob), the record buffer stores length of the
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data, following by memory pointer to the blob data. The pointer is owned
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by the storage engine and is valid until the next operation.
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If a blob column has NULL value, then its length and blob data pointer
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{ return rows2double(ranges+rows); }
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virtual double index_only_read_time(uint32_t keynr, double records);
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virtual ha_rows multi_range_read_info_const(uint32_t keyno, RANGE_SEQ_IF *seq,
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void *seq_init_param,
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void *seq_init_param,
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uint32_t n_ranges, uint32_t *bufsz,
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uint32_t *flags, COST_VECT *cost);
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virtual int multi_range_read_info(uint32_t keyno, uint32_t n_ranges, uint32_t keys,
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This method offers the storage engine, the possibility to store a reference
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to a table name which is going to be used with query cache.
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to a table name which is going to be used with query cache.
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The method is called each time a statement is written to the cache and can
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be used to verify if a specific statement is cachable. It also offers
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the possibility to register a generic (but static) call back function which
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The pushed conditions form a stack (from which one can remove the
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last pushed condition using cond_pop).
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The table handler filters out rows using (pushed_cond1 AND pushed_cond2
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The table handler filters out rows using (pushed_cond1 AND pushed_cond2
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AND ... AND pushed_condN)
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or less restrictive condition, depending on handler's capabilities.
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handler->ha_reset() call empties the condition stack.
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Calls to rnd_init/rnd_end, index_init/index_end etc do not affect the
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virtual const COND *cond_push(const COND *cond) { return cond; }
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This procedure defines if the storage engine supports virtual columns.
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Default false means "not supported".
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virtual bool check_if_supported_virtual_columns(void)
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virtual bool check_if_supported_virtual_columns(void)
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{ return false; }
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virtual void start_bulk_insert(ha_rows)
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virtual int end_bulk_insert(void) { return 0; }
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virtual int index_read(unsigned char *, const unsigned char *,
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virtual int index_read(unsigned char *, const unsigned char *,
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uint32_t, enum ha_rkey_function)
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{ return HA_ERR_WRONG_COMMAND; }
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virtual int index_read_last(unsigned char *, const unsigned char *, uint32_t)
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A Disk-Sweep MRR interface implementation
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This implementation makes range (and, in the future, 'ref') scans to read
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table rows in disk sweeps.
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table rows in disk sweeps.
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Currently it is used by MyISAM and InnoDB. Potentially it can be used with
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any table handler that has non-clustered indexes and on-disk rows.
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void init(handler *h_arg, Table *table_arg)
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table= table_arg;
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int dsmrr_init(handler *h, KEY *key, RANGE_SEQ_IF *seq_funcs,
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void *seq_init_param, uint32_t n_ranges, uint32_t mode,
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int dsmrr_init(handler *h, KEY *key, RANGE_SEQ_IF *seq_funcs,
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void *seq_init_param, uint32_t n_ranges, uint32_t mode,
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1114
HANDLER_BUFFER *buf);
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void dsmrr_close();
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int dsmrr_fill_buffer(handler *h);
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int dsmrr_info(uint32_t keyno, uint32_t n_ranges, uint32_t keys, uint32_t *bufsz,
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uint32_t *flags, COST_VECT *cost);
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ha_rows dsmrr_info_const(uint32_t keyno, RANGE_SEQ_IF *seq,
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ha_rows dsmrr_info_const(uint32_t keyno, RANGE_SEQ_IF *seq,
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void *seq_init_param, uint32_t n_ranges, uint32_t *bufsz,
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uint32_t *flags, COST_VECT *cost);
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bool key_uses_partial_cols(uint32_t keyno);
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bool choose_mrr_impl(uint32_t keyno, ha_rows rows, uint32_t *flags, uint32_t *bufsz,
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bool choose_mrr_impl(uint32_t keyno, ha_rows rows, uint32_t *flags, uint32_t *bufsz,
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COST_VECT *cost);
1129
bool get_disk_sweep_mrr_cost(uint32_t keynr, ha_rows rows, uint32_t flags,
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bool get_disk_sweep_mrr_cost(uint32_t keynr, ha_rows rows, uint32_t flags,
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uint32_t *buffer_size, COST_VECT *cost);
added
removed
drizzled/handler.h
