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BRIN minmax-multi indexes

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Adds BRIN opclasses similar to the existing minmax, except that instead
of summarizing the page range into a single [min,max] range, the summary
consists of multiple ranges and/or points, allowing gaps. This allows
more efficient handling of data with poor correlation to physical
location within the table and/or outlier values, for which the regular
minmax opclassed tend to work poorly.

It's possible to specify the number of values kept for each page range,
either as a single point or an interval boundary.

  CREATE TABLE t (a int);
  CREATE INDEX ON t
   USING brin (a int4_minmax_multi_ops(values_per_range=16));

When building the summary, the values are combined into intervals with
the goal to minimize the "covering" (sum of interval lengths), using a
support procedure computing distance between two values.

Bump catversion, due to various catalog changes.

Author: Tomas Vondra <tomas.vondra@postgresql.org>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>
Reviewed-by: Sokolov Yura <y.sokolov@postgrespro.ru>
Reviewed-by: John Naylor <john.naylor@enterprisedb.com>
Discussion: https://postgr.es/m/c1138ead-7668-f0e1-0638-c3be3237e812@2ndquadrant.com
Discussion: https://postgr.es/m/5d78b774-7e9c-c94e-12cf-fef51cc89b1a%402ndquadrant.com
This commit is contained in:
Tomas Vondra
2021-03-26 13:54:29 +01:00
parent 77b88cd1bb
commit ab596105b5
19 changed files with 5286 additions and 26 deletions
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8
src/include/access/brin_tuple.h
View File

@@ -14,6 +14,11 @@
#include "access/brin_internal.h"
#include "access/tupdesc.h"
/*
* The BRIN opclasses may register serialization callback, in case the on-disk
* and in-memory representations differ (e.g. for performance reasons).
*/
typedef void (*brin_serialize_callback_type) (BrinDesc *bdesc, Datum src, Datum *dst);
/*
* A BRIN index stores one index tuple per page range. Each index tuple
@@ -27,6 +32,9 @@ typedef struct BrinValues
bool bv_hasnulls; /* are there any nulls in the page range? */
bool bv_allnulls; /* are all values nulls in the page range? */
Datum *bv_values; /* current accumulated values */
Datum bv_mem_value; /* expanded accumulated values */
MemoryContext bv_context;
brin_serialize_callback_type bv_serialize;
} BrinValues;
/*