diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/pgwalinspect.sgml | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/doc/src/sgml/pgwalinspect.sgml b/doc/src/sgml/pgwalinspect.sgml index 300ffac3744..eecb6e938b6 100644 --- a/doc/src/sgml/pgwalinspect.sgml +++ b/doc/src/sgml/pgwalinspect.sgml @@ -133,7 +133,7 @@ block_ref | <varlistentry> <term> - <function>pg_get_wal_block_info(start_lsn pg_lsn, end_lsn pg_lsn) returns setof record</function> + <function>pg_get_wal_block_info(start_lsn pg_lsn, end_lsn pg_lsn, show_data boolean DEFAULT true) returns setof record</function> </term> <listitem> @@ -209,11 +209,22 @@ block_fpi_data | <para> The <function>pg_filenode_relation</function> function (see <xref linkend="functions-admin-dblocation"/>) can help you to - determine which block/relation was modified by each WAL record - during original execution + determine which relation was modified during original execution </para> </tip> <para> + It is possible for clients to avoid the overhead of + materializing block data. This may make function execution + significantly faster. When <replaceable>show_data</replaceable> + is set to <literal>false</literal>, <structfield>block_data</structfield> + and <structfield>block_fpi_data</structfield> values are omitted + (that is, the <structfield>block_data</structfield> and + <structfield>block_fpi_data</structfield> <literal>OUT</literal> + arguments are <literal>NULL</literal> for all rows returned). + Obviously, this optimization is only feasible with queries where + block data isn't truly required. + </para> + <para> The function raises an error if <replaceable>start_lsn</replaceable> is not available. </para> |