diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/indexam.sgml | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/doc/src/sgml/indexam.sgml b/doc/src/sgml/indexam.sgml index e3c1539a1e3..dc7d14b60dd 100644 --- a/doc/src/sgml/indexam.sgml +++ b/doc/src/sgml/indexam.sgml @@ -146,6 +146,7 @@ typedef struct IndexAmRoutine amvacuumcleanup_function amvacuumcleanup; amcanreturn_function amcanreturn; /* can be NULL */ amcostestimate_function amcostestimate; + amgettreeheight_function amgettreeheight; /* can be NULL */ amoptions_function amoptions; amproperty_function amproperty; /* can be NULL */ ambuildphasename_function ambuildphasename; /* can be NULL */ @@ -480,6 +481,21 @@ amcostestimate (PlannerInfo *root, <para> <programlisting> +int +amgettreeheight (Relation rel); +</programlisting> + Compute the height of a tree-shaped index. This information is supplied to + the <function>amcostestimate</function> function in + <literal>path->indexinfo->tree_height</literal> and can be used to support + the cost estimation. The result is not used anywhere else, so this + function can actually be used to compute any kind of data (that fits into + an integer) about the index that the cost estimation function might want to + know. If the computation is expensive, it could be useful to cache the + result as part of <literal>RelationData.rd_amcache</literal>. + </para> + + <para> +<programlisting> bytea * amoptions (ArrayType *reloptions, bool validate); |