diff options
| -rw-r--r-- | doc/src/sgml/indexam.sgml | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/doc/src/sgml/indexam.sgml b/doc/src/sgml/indexam.sgml index ef1e37a8260..9a84509f749 100644 --- a/doc/src/sgml/indexam.sgml +++ b/doc/src/sgml/indexam.sgml @@ -1,5 +1,5 @@ <!-- -$PostgreSQL: pgsql/doc/src/sgml/indexam.sgml,v 2.3 2005/03/27 23:52:51 tgl Exp $ +$PostgreSQL: pgsql/doc/src/sgml/indexam.sgml,v 2.4 2005/04/20 22:19:58 tgl Exp $ --> <chapter id="indexam"> @@ -109,7 +109,8 @@ $PostgreSQL: pgsql/doc/src/sgml/indexam.sgml,v 2.3 2005/03/27 23:52:51 tgl Exp $ such a scan should include null rows. In practice this means that indexes that support ordered scans (have <structfield>amorderstrategy</> nonzero) must index nulls, since the planner might decide to use such a - scan as a substitute for sorting. Another restriction is that an index + scan as a substitute for sorting. Such indexes must also be willing to + run a scan with no scan keys at all. Another restriction is that an index access method that supports multiple index columns <emphasis>must</> support indexing null values in columns after the first, because the planner will assume the index can be used for queries on just the first |