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Bug #31228694 FTS QUERY WITH LIMIT HIT AN ASSERT

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Problem:
1. The server terminates abnormally when phrase search doesn't
filter out doc_ids correctly. This problem has been fixed in bug
2. Wrong query result: It's a regression from the bug #22709692 fix.
This fix optimize full-text search query with limit clause.
when FTS expression involves only union operation, we fetch only
number of doc_ids specified with the limit clause.
Fulltext phrase search is not an union operation and we consider
phrase search with plugin parser a union operation.
In phrase search with limit clause, we fetch limited doc_ids for
each token and if any of the selected doc_id does not contain all
tokens in correct order then we do not include that row_id in the
result set.
Therefore phrase search gets fewer number of rows than the qualified
rows exist in the table.

Fix:
Added a condition that phrase search with plugin parser is not a
union operation.

RB: 24925
Reviewed by : Annamalai Gurusami <annamalai.gurusami@oracle.com>

This is a cherry-pick of
mysql/mysql-server@5549920b7a
without a test case, because the test case depends on an n-gram
tokenizer that will be missing from MariaDB until MDEV-10267 is added.
This commit is contained in:
Sachin Agarwal 2020-08-28 18:18:25 +05:30 • committed by Marko Mäkelä
commit 1ff8588c3f
1 changed files with 5 additions and 3 deletions
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8
storage/innobase/fts/fts0ast.cc
View file

@ -1,6 +1,6 @@
/*****************************************************************************
Copyright (c) 2007, 2018, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2007, 2020, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2018, MariaDB Corporation.
This program is free software; you can redistribute it and/or modify it under
@ -557,8 +557,7 @@ fts_ast_node_check_union(
fts_ast_node_t* node)
{
if (node->type == FTS_AST_LIST
|| node->type == FTS_AST_SUBEXP_LIST
|| node->type == FTS_AST_PARSER_PHRASE_LIST) {
|| node->type == FTS_AST_SUBEXP_LIST) {
for (node = node->list.head; node; node = node->next) {
if (!fts_ast_node_check_union(node)) {
@ -566,6 +565,9 @@ fts_ast_node_check_union(
}
}
} else if (node->type == FTS_AST_PARSER_PHRASE_LIST) {
/* Phrase search for plugin parser */
return(false);
} else if (node->type == FTS_AST_OPER
&& (node->oper == FTS_IGNORE
|| node->oper == FTS_EXIST)) {