diff options
Diffstat (limited to 'src/backend/access/gist/README')
| -rw-r--r-- | src/backend/access/gist/README | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/src/backend/access/gist/README b/src/backend/access/gist/README index 25cab0047b6..efb2730e181 100644 --- a/src/backend/access/gist/README +++ b/src/backend/access/gist/README @@ -26,6 +26,7 @@ The current implementation of GiST supports: * Concurrency * Recovery support via WAL logging * Buffering build algorithm + * Sorted build method The support for concurrency implemented in PostgreSQL was developed based on the paper "Access Methods for Next-Generation Database Systems" by @@ -414,6 +415,21 @@ emptied yet; tuples never move upwards in the tree. The final emptying loops through buffers at a given level until all buffers at that level have been emptied, and then moves down to the next level. +Sorted build method +------------------- + +Sort all input tuples, pack them into GiST leaf pages in the sorted order, +and create downlinks and internal pages as we go. This method builds the index +from the bottom up, similar to how the B-tree index is built. + +The sorted method is used if the operator classes for all columns have a +"sortsupport" defined. Otherwise, we fall back on inserting tuples one by one +with optional buffering. + +Sorting GiST build requires good linearization of the sort opclass. That is not +always the case in multidimensional data. To tackle the anomalies, we buffer +index tuples and apply a picksplit function that can be multidimensional-aware. + Bulk delete algorithm (VACUUM) ------------------------------ |