-Gevel contrib module provides several functions useful for analyzing GiST index.
+Gevel contrib module provides several functions useful for analyzing GiST and GIN index.
[Online version] of this document (http://www.sai.msu.su/~megera/oddmuse/index.cgi/Gevel)
-Caution: This module was designed for developers of GiST based indices !
+Caution: This module was designed for advanced users of GIN, GiST and SP-GiST indices !
Authors
* Oleg Bartunov <oleg@sai.msu.su>, Moscow, Moscow University, Russia
- * Teodor Sigaev <teodor@sigaev.ru>, Moscow, Delta-Soft Ltd.,Russia
+ * Teodor Sigaev <teodor@sigaev.ru>, Moscow, Moscow University, Russia
License
1 | t | (31179,50040),(28113,25556)
1 | t | (28048,49694),(25000,25000)
(29 rows)
+
+ * spgist_stat(INDEXNAME) - show some statistics about SP-GiST tree
+
+# SELECT spgist_stat('spgist_idx');
+ spgist_stat
+----------------------------------
+ totalPages: 21 +
+ deletedPages: 0 +
+ innerPages: 3 +
+ leafPages: 18 +
+ emptyPages: 1 +
+ usedSpace: 121.27 kbytes+
+ freeSpace: 46.07 kbytes +
+ fillRatio: 72.47% +
+ leafTuples: 3669 +
+ innerTuples: 20 +
+ innerAllTheSame: 0 +
+ leafPlaceholders: 569 +
+ innerPlaceholders: 0 +
+ leafRedirects: 0 +
+ innerRedirects: 0
+
+ * spgist_print(INDEXNAME) - prints objects stored in GiST tree,
+ works only if objects in index have textual representation
+ (type_out functions should be implemented for given object type).
+ Note 1. in example below we used quad_point_ops which uses point
+ for leaf and prefix value, but doesn't use node_label at all.
+ Use type 'int' as dummy type for prefix or/and node_label.
+ Note 2
+ quad_point_ops: prefix point, node_label int, leaf_value point
+ kd_point_ops: prefix float, node_label int, leaf_value point
+ text_ops: prefix text, node_label char, leaf_value text
+
+# SELECT * FROM spgist_print('spgist_idx') as t
+ (
+ tid tid,
+ node_n int,
+ level int,
+ tid_pointer tid,
+ prefix point,
+ node_label int,
+ leaf_value point
+ ) where level = 1;
+ tid | node_n | level | tid_pointer | prefix | node_label | leaf_value
+-------+--------+-------+-------------+-------------------------------------+------------+------------
+ (1,1) | 0 | 1 | (5,4) | (24530.2070484581,23595.7092511013) | |
+ (1,1) | 1 | 1 | (5,3) | (24530.2070484581,23595.7092511013) | |
+ (1,1) | 2 | 1 | (5,2) | (24530.2070484581,23595.7092511013) | |
+ (1,1) | 3 | 1 | (5,1) | (24530.2070484581,23595.7092511013) | |
+
+ * gin_stat(INDEXNAME) prints estimated counts for each indexed values
+ Note: since 8.4 gin_stat function has gin_stat(INDEXNAME, COLNUMBER)
+ prototype, single-argument function will return result for a first
+ column of index
+
+# SELECT * FROM gin_stat('gin_idx') as t(value int, nrow int) where nrow > 250;
+ value | nrow
+ -------+------
+ 31 | 254
+ 47 | 251
+ 52 | 257
+ 59 | 259
+ (4 rows)
+
+ * bigint gin_count_estimate(INDEXNAME, TSQUERY) outputs number of indexed
+ rows matched query. It doesn't touch heap at all.
+
+# select gin_count_estimate('qq', 'star');
+ gin_count_estimate
+--------------------
+ 790
+(1 row)
+
projects / gevel.git / blobdiff