diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/spgist.sgml | 38 |
1 files changed, 28 insertions, 10 deletions
diff --git a/doc/src/sgml/spgist.sgml b/doc/src/sgml/spgist.sgml index dcc3cc2d733..0202dbcdd5a 100644 --- a/doc/src/sgml/spgist.sgml +++ b/doc/src/sgml/spgist.sgml @@ -439,8 +439,8 @@ CREATE FUNCTION my_inner_consistent(internal, internal) RETURNS void ... <programlisting> typedef struct spgInnerConsistentIn { - StrategyNumber strategy; /* operator strategy number */ - Datum query; /* operator's RHS value */ + ScanKey scankeys; /* array of operators and comparison values */ + int nkeys; /* length of array */ Datum reconstructedValue; /* value reconstructed at parent */ int level; /* current level (counting from zero) */ @@ -463,8 +463,17 @@ typedef struct spgInnerConsistentOut } spgInnerConsistentOut; </programlisting> - <structfield>strategy</> and - <structfield>query</> describe the index search condition. + The array <structfield>scankeys</>, of length <structfield>nkeys</>, + describes the index search condition(s). These conditions are + combined with AND — only index entries that satisfy all of + them are interesting. (Note that <structfield>nkeys</> = 0 implies + that all index entries satisfy the query.) Usually the consistent + function only cares about the <structfield>sk_strategy</> and + <structfield>sk_argument</> fields of each array entry, which + respectively give the indexable operator and comparison value. + In particular it is not necessary to check <structfield>sk_flags</> to + see if the comparison value is NULL, because the SP-GiST core code + will filter out such conditions. <structfield>reconstructedValue</> is the value reconstructed for the parent tuple; it is <literal>(Datum) 0</> at the root level or if the <function>inner_consistent</> function did not provide a value at the @@ -527,8 +536,8 @@ CREATE FUNCTION my_leaf_consistent(internal, internal) RETURNS bool ... <programlisting> typedef struct spgLeafConsistentIn { - StrategyNumber strategy; /* operator strategy number */ - Datum query; /* operator's RHS value */ + ScanKey scankeys; /* array of operators and comparison values */ + int nkeys; /* length of array */ Datum reconstructedValue; /* value reconstructed at parent */ int level; /* current level (counting from zero) */ @@ -544,8 +553,17 @@ typedef struct spgLeafConsistentOut } spgLeafConsistentOut; </programlisting> - <structfield>strategy</> and - <structfield>query</> define the index search condition. + The array <structfield>scankeys</>, of length <structfield>nkeys</>, + describes the index search condition(s). These conditions are + combined with AND — only index entries that satisfy all of + them satisfy the query. (Note that <structfield>nkeys</> = 0 implies + that all index entries satisfy the query.) Usually the consistent + function only cares about the <structfield>sk_strategy</> and + <structfield>sk_argument</> fields of each array entry, which + respectively give the indexable operator and comparison value. + In particular it is not necessary to check <structfield>sk_flags</> to + see if the comparison value is NULL, because the SP-GiST core code + will filter out such conditions. <structfield>reconstructedValue</> is the value reconstructed for the parent tuple; it is <literal>(Datum) 0</> at the root level or if the <function>inner_consistent</> function did not provide a value at the @@ -566,8 +584,8 @@ typedef struct spgLeafConsistentOut <structfield>leafValue</> must be set to the value originally supplied to be indexed for this leaf tuple. Also, <structfield>recheck</> may be set to <literal>true</> if the match - is uncertain and so the operator must be re-applied to the actual heap - tuple to verify the match. + is uncertain and so the operator(s) must be re-applied to the actual + heap tuple to verify the match. </para> </listitem> </varlistentry> |