diff options
Diffstat (limited to 'src/include/nodes/pathnodes.h')
| -rw-r--r-- | src/include/nodes/pathnodes.h | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h index ac3af528bc6..6e034960896 100644 --- a/src/include/nodes/pathnodes.h +++ b/src/include/nodes/pathnodes.h @@ -1402,6 +1402,18 @@ typedef struct JoinDomain * entry: consider SELECT random() AS a, random() AS b ... ORDER BY b,a. * So we record the SortGroupRef of the originating sort clause. * + * Derived equality clauses are stored in ec_derives_list. For small queries, + * this list is scanned directly during lookup. For larger queries -- e.g., + * with many partitions or joins -- a hash table (ec_derives_hash) is built + * when the list grows beyond a threshold, for faster lookup. When present, + * the hash table contains the same RestrictInfos and is maintained alongside + * the list. We retain the list even when the hash is used to simplify + * serialization (e.g., in _outEquivalenceClass()) and support + * EquivalenceClass merging. + * + * In contrast, ec_sources holds equality clauses that appear directly in the + * query. These are typically few and do not require a hash table for lookup. + * * NB: if ec_merged isn't NULL, this class has been merged into another, and * should be ignored in favor of using the pointed-to class. * @@ -1421,7 +1433,10 @@ typedef struct EquivalenceClass Oid ec_collation; /* collation, if datatypes are collatable */ List *ec_members; /* list of EquivalenceMembers */ List *ec_sources; /* list of generating RestrictInfos */ - List *ec_derives; /* list of derived RestrictInfos */ + List *ec_derives_list; /* list of derived RestrictInfos */ + struct derives_hash *ec_derives_hash; /* optional hash table for fast + * lookup; contains same + * RestrictInfos as list */ Relids ec_relids; /* all relids appearing in ec_members, except * for child members (see below) */ bool ec_has_const; /* any pseudoconstants in ec_members? */ |