diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/catalogs.sgml | 9 | ||||
| -rw-r--r-- | doc/src/sgml/indexam.sgml | 19 |
2 files changed, 20 insertions, 8 deletions
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml index ae6dfbd8a55..a68799334ad 100644 --- a/doc/src/sgml/catalogs.sgml +++ b/doc/src/sgml/catalogs.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.178 2008/10/06 13:59:37 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.179 2008/10/17 22:10:29 tgl Exp $ --> <!-- Documentation of the system catalogs, directed toward PostgreSQL developers --> @@ -402,6 +402,13 @@ </row> <row> + <entry><structfield>amcanbackward</structfield></entry> + <entry><type>bool</type></entry> + <entry></entry> + <entry>Does the access method support backward scanning?</entry> + </row> + + <row> <entry><structfield>amcanunique</structfield></entry> <entry><type>bool</type></entry> <entry></entry> diff --git a/doc/src/sgml/indexam.sgml b/doc/src/sgml/indexam.sgml index 393ccfa2dd1..db16c1d4ee5 100644 --- a/doc/src/sgml/indexam.sgml +++ b/doc/src/sgml/indexam.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/indexam.sgml,v 2.27 2008/08/14 18:47:58 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/indexam.sgml,v 2.28 2008/10/17 22:10:29 tgl Exp $ --> <chapter id="indexam"> <title>Index Access Method Interface Definition</title> @@ -474,15 +474,20 @@ amrestrpos (IndexScanDesc scan); normally would. (This will only occur for access methods that advertise they support ordered scans.) After the first call, <function>amgettuple</> must be prepared to advance the scan in - either direction from the most recently returned entry. + either direction from the most recently returned entry. (But if + <structname>pg_am</>.<structfield>amcanbackward</> is false, all subsequent + calls will have the same direction as the first one.) </para> <para> - The access method must support <quote>marking</> a position in a scan - and later returning to the marked position. The same position might be - restored multiple times. However, only one position need be remembered - per scan; a new <function>ammarkpos</> call overrides the previously - marked position. + Access methods that support ordered scans must support <quote>marking</> a + position in a scan and later returning to the marked position. The same + position might be restored multiple times. However, only one position need + be remembered per scan; a new <function>ammarkpos</> call overrides the + previously marked position. An access method that does not support + ordered scans should still provide mark and restore functions in + <structname>pg_am</>, but it is sufficient to have them throw errors if + called. </para> <para> |