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Fix formatting on pg_array_column_postgrest

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Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>
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Pierre-Yves Chibon 2021-02-17 09:59:08 +01:00
parent 4f0a08ac18
commit 5c96c94175
1 changed files with 7 additions and 7 deletions
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14
docs/datanommer_datagrepper/pg_array_column_postgrest.rst
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@ -1,5 +1,5 @@
Using the array type for user and package queries
===============================
Using the array type for user and package queries
=================================================
Currently, we use auxiliary tables to query for messages related to packages or users,
in the standard RDBS fashion.
@ -29,7 +29,7 @@ To add new column
To populate it
::
update messages2 set packages=t_agg.p_agg from
update messages2 set packages=t_agg.p_agg from
(select msg, array_agg(package) as p_agg from package_messages group by msg) as t_agg where messages.id=t_agg.msg;
We need to enable the btree_gin extension to be able to create index with array as well as timestamp
@ -58,13 +58,13 @@ A simple membership:
A simple membership ordered by time.
::
/messages_ts?order=timestamp.desc&packages=ov.{{kernel}}
/messages_ts?order=timestamp.desc&packages=ov.{{kernel}}
Findings
--------
Querying just the package membership
~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The queries were surprisingly fast, with maximum under 4 seconds and
mean around half a second. This encouraged us to do further experiments.
@ -78,7 +78,7 @@ Results ::
Time per Request - mean: 0.522946, min: 0.000000, max: 3.907548
Querying just the package membership ordered by timestamp desc
~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Usually we want to see most recent messages. So we ammended the query,
to include "order by timestamp desc". The result was less encouraging,
@ -95,7 +95,7 @@ Results ::
Time per Request - mean: 7.474040, min: 0.000000, max: 99.880939
Conclusion
--------------
----------
While array support seems interesting, and for simple queries very fast, indexes that require ordering
don't seem to be supported. This makes strong case against using them.