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Change predecence of phrase operator.

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<-> operator now have higher predecence than & (AND) operator. This change
was motivated by unexpected difference of similar queries:
'a & b <-> c'::tsquery and 'b <-> c & a'. Before first query means
(a & b) <-> c and second one - '(b <-> c) & a', now phrase operator evaluates
first.

Per suggestion from Tom Lane 32260.1465402409@sss.pgh.pa.us
This commit is contained in:
Teodor Sigaev
2016-06-27 20:55:24 +03:00
parent 3dbbd0f02a
commit 6734a1cacd
6 changed files with 121 additions and 134 deletions
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17
src/backend/utils/adt/tsquery_cleanup.c
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@ -25,11 +25,18 @@ typedef struct NODE
QueryItem *valnode;
} NODE;
/* Non-operator nodes have fake (but highest) priority */
/*
* To simplify walking on query tree and pushing down of phrase operator
* we define some fake priority here: phrase operator has highest priority
* of any other operators (and we believe here that OP_PHRASE is a highest
* code of operations) and value node has ever highest priority.
* Priority values of other operations don't matter until they are less than
* phrase operator and value node.
*/
#define VALUE_PRIORITY (OP_COUNT + 1)
#define NODE_PRIORITY(x) \
( ((x)->valnode->qoperator.type == QI_OPR) ? \
QO_PRIORITY((x)->valnode) : \
TOP_PRIORITY )
(x)->valnode->qoperator.oper : VALUE_PRIORITY )
/*
* make query tree from plain view of query
@ -416,6 +423,10 @@ normalize_phrase_tree(NODE *node)
node->left = normalize_phrase_tree(node->left);
node->right = normalize_phrase_tree(node->right);
/*
* if subtree contains only nodes with higher "priority" then
* we are done. See comment near NODE_PRIORITY()
*/
if (NODE_PRIORITY(node) <= NODE_PRIORITY(node->right) &&
NODE_PRIORITY(node) <= NODE_PRIORITY(node->left))
return node;