On Tue, May 3, 2016 at 8:09 PM, Maxim Boguk <[email protected]> wrote:
> Hi,
>
> I started with empty table with index over
> custom_fields | jsonb
> field
> defined as:
> "idx_learners_custom_fields" gin (custom_fields)
> Globally gin_pending_list_limit set to 2MB.
> Database version is 9.5.2.
>
> Now question:
> If table populated with 1M records in single transaction then the final
> size of the GIN index is:
> 4265 MB
> but after I performed reindex index idx_learners_custom_fields;
> the index size had been reduced 15x to 295 MB.
>
> Is this behavior expected?
>
It's look easy to reproduce.
I can send a sample dataset for analyze.
drop table if exists test;
create table test (custom_fields jsonb);
create index test_gin_key on test USING GIN(custom_fields);
insert into test select custom_fields from public.learners;
INSERT 0 1000000
\di+ test_gin_key
List of relations
Schema | Name | Type | Owner | Table | Size | Description
--------+--------------+-------+----------+-------+---------+-------------
public | test_gin_key | index | postgres | test | 4211 MB |
reindex index test_gin_key;
\di+ test_gin_key
List of relations
Schema | Name | Type | Owner | Table | Size | Description
--------+--------------+-------+----------+-------+--------+-------------
public | test_gin_key | index | postgres | test | 295 MB |
--
Maxim Boguk
Senior Postgresql DBA
http://www.postgresql-consulting.com/
Phone RU: +7 910 405 4718
Phone AU: +61 45 218 5678
LinkedIn: http://www.linkedin.com/pub/maksym-boguk/80/b99/b1b
Skype: maxim.boguk
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"People problems are solved with people.
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