indexing Questions

Trying to get the last object from a JSON list

October 1, 2024
SebMa
2 Answers

I have the following JSON data : $ cat toto.json { "method": "GET", "path": "/users/sign_in", "status": 500, "exception.class": "NoMethodError", "exception.message": "undefined method `user_azure_activedirectory_v2_omniauth_authorize_path' for #<ActionDispatch::Routing::RoutesProxy:0x00007d6fe7cfd0d0 @scope=#<SessionsController:0x00000000186758>, @routes=#<ActionDispatch::Routing::RouteSet:0x00007d701b857b28>, @helpers=#<Module:0x00007d701b6f38b8>, @script_namer=nil>" } { "method": "GET", "path": "/users/sign_in", "status": 500, "exception.class": "NoMethodError", "exception.message":…

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Postgresql – Slow query when using LIMIT for pagination

September 27, 2024
Huluti
2 Answers

I need some help to optimize my filtering/pagination system under Symfony/PostgreSQL. I have a table "link" with ~5M rows and this query used for the pagination system with https://github.com/KnpLabs/KnpPaginatorBundle. SELECT * FROM link l0_ WHERE l0_.team_id = 21 AND l0_.folder_id…

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Mysql – indexing a column with mostly null values

September 24, 2024
idan ahal
2 Answers

I have a very big table with a column that has mostly null values. I query this table a lot with x_column is not null condition. I wonder how I should index it and what is the best way to…

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Postgresql – Change to Postgres indexing scheme for IS NOT NULL?

September 18, 2024
just-some-questions
2 Answers

I have a Postgres table that has numerous columns which frequently show up in the where clause of select queries. The table has been indexed accordingly, with indexes on all of these columns (mostly single-column indexes, but with some composite…

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Postgresql – Postgre join query not using expected index

September 16, 2024
Raven
2 Answers

I have a very simple two-table set in Postgre 16.0: CREATE TABLE fk_table ( fk_id INT PRIMARY KEY , fk_name VARCHAR(50) ); CREATE TABLE main_table ( id INT PRIMARY KEY , date TIMESTAMP , fk INT REFERENCES fk_table(fk_id) --, tens…

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Index not hit in mysql

September 6, 2024
Vitor Lins
2 Answers

When I select all columns, the indexing does not work, but if I select just a few columns, it does. mysql> explain SELECT * FROM fatura USE INDEX (datapago_serv_pago) WHERE id_servidor = 10 AND pago = '1' AND data_pago <=…

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Javascript – How to compare two arrays at the index and also include null values in the new array output

September 6, 2024
too twiisted
3 Answers

So I am very new to coding and have run into an issue when it comes to comparing arrays, especially ones that are nested and trying to pull out values that match using their indices into a new array. Say…

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Postgresql – How to search for the acronym of a string column in an indexable way

August 30, 2024
Daniel
2 Answers

I'm working on an express.js project, using Sequelize as the orm, and postgres as the engine. I'm working on improving the performance of a slow select query that does many things, and one of them is comparing the acronym of…

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Mysql – can a sql sentence use index covering and index condition pushdown simultaneously？

August 24, 2024
Lucien
2 Answers

When the query does not meet the conditions for index coverage,if Innodb will use index condition pushdown by auto? or how to explain these two thing by simple word or example.

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MySQL prefix index on datetime column

August 23, 2024
John Rix
2 Answers

I have a log table with timestamped (DATETIME) rows in the millions which I occasionally need to search by date or date range. I have an index on the timestamp column at present for the purpose. However, I am wondering…

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