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| author | Alexander Korotkov <akorotkov@postgresql.org> | 2020-12-20 07:20:33 +0300 |
|---|---|---|
| committer | Alexander Korotkov <akorotkov@postgresql.org> | 2020-12-20 07:20:33 +0300 |
| commit | 6df7a9698bb036610c1e8c6d375e1be38cb26d5f (patch) | |
| tree | dc5985310422e2b41e06bc1770f9e384e0bd6525 /src/include/access/tupmacs.h | |
| parent | 08b01d4dd982b491a2f9641804b368185b8f4c53 (diff) | |
Multirange datatypes
Multiranges are basically sorted arrays of non-overlapping ranges with
set-theoretic operations defined over them.
Since v14, each range type automatically gets a corresponding multirange
datatype. There are both manual and automatic mechanisms for naming multirange
types. Once can specify multirange type name using multirange_type_name
attribute in CREATE TYPE. Otherwise, a multirange type name is generated
automatically. If the range type name contains "range" then we change that to
"multirange". Otherwise, we add "_multirange" to the end.
Implementation of multiranges comes with a space-efficient internal
representation format, which evades extra paddings and duplicated storage of
oids. Altogether this format allows fetching a particular range by its index
in O(n).
Statistic gathering and selectivity estimation are implemented for multiranges.
For this purpose, stored multirange is approximated as union range without gaps.
This field will likely need improvements in the future.
Catversion is bumped.
Discussion: https://postgr.es/m/CALNJ-vSUpQ_Y%3DjXvTxt1VYFztaBSsWVXeF1y6gTYQ4bOiWDLgQ%40mail.gmail.com
Discussion: https://postgr.es/m/a0b8026459d1e6167933be2104a6174e7d40d0ab.camel%40j-davis.com#fe7218c83b08068bfffb0c5293eceda0
Author: Paul Jungwirth, revised by me
Reviewed-by: David Fetter, Corey Huinker, Jeff Davis, Pavel Stehule
Reviewed-by: Alvaro Herrera, Tom Lane, Isaac Morland, David G. Johnston
Reviewed-by: Zhihong Yu, Alexander Korotkov
Diffstat (limited to 'src/include/access/tupmacs.h')
| -rw-r--r-- | src/include/access/tupmacs.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/src/include/access/tupmacs.h b/src/include/access/tupmacs.h index 70157cf90ab..c262265b951 100644 --- a/src/include/access/tupmacs.h +++ b/src/include/access/tupmacs.h @@ -139,8 +139,8 @@ * * we need to estimate alignment padding cost abstractly, ie without * reference to a real tuple. We must assume the worst case that * all varlenas are aligned. - * * within arrays, we unconditionally align varlenas (XXX this should be - * revisited, probably). + * * within arrays and multiranges, we unconditionally align varlenas (XXX this + * should be revisited, probably). * * The attalign cases are tested in what is hopefully something like their * frequency of occurrence. |