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author | Sergey Petrunya <psergey@askmonty.org> | 2010-11-03 00:09:28 +0300 |
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committer | Sergey Petrunya <psergey@askmonty.org> | 2010-11-03 00:09:28 +0300 |
commit | c46450de724449466060a0934de2c4244674aa76 (patch) | |
tree | 35ea268b458df64a1e5bbbe4880a61552184c159 /sql/multi_range_read.cc | |
parent | 1654780f2d2de3c6b0b8190dba7993523d4fdf81 (diff) | |
download | mariadb-git-c46450de724449466060a0934de2c4244674aa76.tar.gz |
Code cleanup
Diffstat (limited to 'sql/multi_range_read.cc')
-rw-r--r-- | sql/multi_range_read.cc | 105 |
1 files changed, 57 insertions, 48 deletions
diff --git a/sql/multi_range_read.cc b/sql/multi_range_read.cc index 72099bb0967..fa7f627760a 100644 --- a/sql/multi_range_read.cc +++ b/sql/multi_range_read.cc @@ -282,8 +282,20 @@ scan_it_again: DBUG_RETURN(result); } +/**************************************************************************** + * Mrr_*_reader classes (building blocks for DS-MRR) + ***************************************************************************/ -/***** Mrr_*_reader classes **************************************************/ +int Mrr_simple_index_reader::init(handler *h_arg, RANGE_SEQ_IF *seq_funcs, + void *seq_init_param, uint n_ranges, + uint mode, Buffer_manager *buf_manager_arg) +{ + HANDLER_BUFFER no_buffer = {NULL, NULL, NULL}; + h= h_arg; + res= 0; + return h->handler::multi_range_read_init(seq_funcs, seq_init_param, n_ranges, + mode, &no_buffer); +} int Mrr_simple_index_reader::get_next(char **range_info) { @@ -297,44 +309,35 @@ int Mrr_simple_index_reader::get_next(char **range_info) return res; } -int Mrr_simple_index_reader::init(handler *h_arg, RANGE_SEQ_IF *seq_funcs, - void *seq_init_param, uint n_ranges, - uint mode, Buffer_manager *buf_manager_arg) -{ - HANDLER_BUFFER no_buffer = {NULL, NULL, NULL}; - h= h_arg; - res= 0; - return h->handler::multi_range_read_init(seq_funcs, seq_init_param, n_ranges, - mode, &no_buffer); -} /** - DS-MRR/CPK: multi_range_read_next() function - - @param range_info OUT identifier of range that the returned record belongs to + @brief Get next index record + + @param range_info OUT identifier of range that the returned record belongs to @note - This function walks over key buffer and does index reads, i.e. it produces - {current_record, range_id} pairs. - - The function has the same call contract like multi_range_read_next()'s. - We actually iterate over nested sequences: - - a disjoint sequence of index ranges - - each range has multiple records - - each record goes into multiple identical ranges. + - an ordered sequence of groups of identical keys + - each key group has key value, which has multiple matching records + - thus, each record matches all members of the key group @retval 0 OK, next record was successfully read @retval HA_ERR_END_OF_FILE End of records @retval Other Some other error */ -int Mrr_ordered_index_reader::get_next(char **range_info_arg) +int Mrr_ordered_index_reader::get_next(char **range_info) { DBUG_ENTER("Mrr_ordered_index_reader::get_next"); - if (!know_key_tuple_params) /* We're in startup phase */ + if (!know_key_tuple_params) + { + /* + We're at the very start, haven't filled the buffer or even know what + will be there. Force the caller to call refill_buffer(): + */ DBUG_RETURN(HA_ERR_END_OF_FILE); + } while (1) { @@ -374,24 +377,21 @@ int Mrr_ordered_index_reader::get_next(char **range_info_arg) /* Go get another (record, range_id) combination */ } /* while */ - memcpy(range_info_arg, cur_range_info, sizeof(void*)); + memcpy(range_info, cur_range_info, sizeof(void*)); DBUG_RETURN(0); } /** - DS-MRR/CPK: Fill the buffer with (lookup_tuple, range_id) pairs and sort - - Enumerate the input range (=key) sequence, fill the key buffer with - (lookup_key, range_id) pairs and sort it. - - When this function returns, either - - key buffer is non-empty, or - - key buffer is empty and source range sequence is exhausted - + Fill the buffer with (lookup_tuple, range_id) pairs and sort + @note - dsmrr_eof is set to indicate whether we've exhausted the list of ranges - we're scanning. + We don't know lookup_tuple before we get the first key from + mrr_funcs.get_next(). Not knowing tuple length means we can't setup the + key buffer (in particular, which part of the buffer space it should occupy + when we have both key and rowid buffers). This problem is solved by having + know_key_tuple_params variabe, and buf_manager, which we ask to set/reset + buffers for us. */ int Mrr_ordered_index_reader::refill_buffer() @@ -521,7 +521,7 @@ int Mrr_ordered_rndpos_reader::refill_buffer() if (index_reader_exhausted) DBUG_RETURN(HA_ERR_END_OF_FILE); - while ((res= refill2() == HA_ERR_END_OF_FILE)) + while ((res= refill_from_key_buffer() == HA_ERR_END_OF_FILE)) { if ((res= index_reader->refill_buffer())) { @@ -534,13 +534,23 @@ int Mrr_ordered_rndpos_reader::refill_buffer() } -/* This one refills without calling index_reader->refill_buffer(). */ -int Mrr_ordered_rndpos_reader::refill2() +void Mrr_index_reader::position() +{ + h->position(h->get_table()->record[0]); +} + + +/* + @brief Try to refill the rowid buffer without calling + index_reader->refill_buffer(). +*/ + +int Mrr_ordered_rndpos_reader::refill_from_key_buffer() { char *range_info; uchar **range_info_ptr= (uchar**)&range_info; int res; - DBUG_ENTER("Mrr_ordered_rndpos_reader::refill2"); + DBUG_ENTER("Mrr_ordered_rndpos_reader::refill_from_key_buffer"); DBUG_ASSERT(rowid_buffer->is_empty()); index_rowid= index_reader->get_rowid_ptr(); @@ -559,7 +569,7 @@ int Mrr_ordered_rndpos_reader::refill2() break; /* Put rowid, or {rowid, range_id} pair into the buffer */ - index_reader->h->position(index_reader->h->get_table()->record[0]); + index_reader->position(); rowid_buffer->write(); } @@ -574,10 +584,12 @@ int Mrr_ordered_rndpos_reader::refill2() } -/** - DS-MRR implementation: multi_range_read_next() function. +/* + Get the next record+range_id using ordered array of rowid+range_id pairds - Calling convention is like multi_range_read_next() has. + @note + Since we have sorted rowids, we try not to make multiple rnd_pos() calls + with the same rowid value. */ int Mrr_ordered_rndpos_reader::get_next(char **range_info) @@ -658,11 +670,8 @@ int Mrr_ordered_rndpos_reader::get_next(char **range_info) } -/************ Mrr_*_reader classes end ***************************************/ - - /**************************************************************************** - * DS-MRR implementation + * Top-level DS-MRR implementation functions (the ones called by storage engine) ***************************************************************************/ /** |