diff options
| author | Teodor Sigaev | 2007-01-31 15:09:45 +0000 |
|---|---|---|
| committer | Teodor Sigaev | 2007-01-31 15:09:45 +0000 |
| commit | d4c6da152782b580b24cd8b4054eb1b7fb72c5a0 (patch) | |
| tree | 23db426588b5ff2a39981393a3cc4b48397b4294 /doc/src/sgml | |
| parent | 147a3ce149088c913b152e7d37bb92f61bb068dd (diff) | |
Allow GIN's extractQuery method to signal that nothing can satisfy the query.
In this case extractQuery should returns -1 as nentries. This changes
prototype of extractQuery method to use int32* instead of uint32* for
nentries argument.
Based on that gincostestimate may see two corner cases: nothing will be found
or seqscan should be used.
Per proposal at http://archives.postgresql.org/pgsql-hackers/2007-01/msg01581.php
PS tsearch_core patch should be sightly modified to support changes, but I'm
waiting a verdict about reviewing of tsearch_core patch.
Diffstat (limited to 'doc/src/sgml')
| -rw-r--r-- | doc/src/sgml/gin.sgml | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/doc/src/sgml/gin.sgml b/doc/src/sgml/gin.sgml index c2bbad42bfa..32919e58711 100644 --- a/doc/src/sgml/gin.sgml +++ b/doc/src/sgml/gin.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/gin.sgml,v 2.7 2006/12/01 23:46:46 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/gin.sgml,v 2.8 2007/01/31 15:09:45 teodor Exp $ --> <chapter id="GIN"> <title>GIN Indexes</title> @@ -77,7 +77,7 @@ </varlistentry> <varlistentry> - <term>Datum* extractValue(Datum inputValue, uint32 *nkeys)</term> + <term>Datum* extractValue(Datum inputValue, int32 *nkeys)</term> <listitem> <para> Returns an array of keys given a value to be indexed. The @@ -87,7 +87,7 @@ </varlistentry> <varlistentry> - <term>Datum* extractQuery(Datum query, uint32 *nkeys, + <term>Datum* extractQuery(Datum query, int32 *nkeys, StrategyNumber n)</term> <listitem> <para> @@ -100,6 +100,12 @@ to consult <literal>n</> to determine the data type of <literal>query</> and the key values that need to be extracted. The number of returned keys must be stored into <literal>*nkeys</>. + If number of keys is equal to zero then <function>extractQuery</> + should store 0 or -1 into <literal>*nkeys</>. 0 means that any + row matches the <literal>query</> and sequence scan should be + produced. -1 means nothing can satisfy <literal>query</>. + Choice of value should be based on semantics meaning of operation with + given strategy number. </para> </listitem> </varlistentry> |