diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/pgfreespacemap.sgml | 2 | ||||
| -rw-r--r-- | doc/src/sgml/pgstattuple.sgml | 4 |
2 files changed, 5 insertions, 1 deletions
diff --git a/doc/src/sgml/pgfreespacemap.sgml b/doc/src/sgml/pgfreespacemap.sgml index 0122d278e39..0bcf79b02b4 100644 --- a/doc/src/sgml/pgfreespacemap.sgml +++ b/doc/src/sgml/pgfreespacemap.sgml @@ -61,6 +61,8 @@ The values stored in the free space map are not exact. They're rounded to precision of 1/256th of <symbol>BLCKSZ</symbol> (32 bytes with default <symbol>BLCKSZ</symbol>), and they're not kept fully up-to-date as tuples are inserted and updated. + In addition, small tables don't have a free space map, so these functions + will return zero even if free space is available. </para> <para> diff --git a/doc/src/sgml/pgstattuple.sgml b/doc/src/sgml/pgstattuple.sgml index b17b3c59e0d..8797131c643 100644 --- a/doc/src/sgml/pgstattuple.sgml +++ b/doc/src/sgml/pgstattuple.sgml @@ -527,7 +527,9 @@ approx_free_percent | 2.09 bit set, then it is assumed to contain no dead tuples). For such pages, it derives the free space value from the free space map, and assumes that the rest of the space on the page is taken up by live - tuples. + tuples. Small tables don't have a free space map, so in that case + this function will report zero free space, likewise inflating the + approximate tuple length. </para> <para> |