Jan Urbański wrote:
Here's a WIP patch implementing an oprrest function for tsvector @@
tsquery and tsquery @@ tsvector.
The idea is (quoting a comment)
/*
* Traverse the tsquery preorder, calculating selectivity as:
*
* selec(left_oper) * selec(right_oper) in AND nodes,
*
* selec(left_oper) + selec(right_oper) -
* selec(left_oper) * selec(right_oper) in OR nodes,
*
* 1 - select(oper) in NOT nodes
*
* freq[val] in VAL nodes, if the value is in MCELEM
* min(freq[MCELEM]) / 2 in VAL nodes, if it is not
Seems reasonable.
*
* Implementation-wise, we sort the MCELEM array to use binary
* search on it.
*/
Would it be possible to store the array in sorted order, to avoid
sorting it on every invocation of tssel?
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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