- 01 1月, 2020 1 次提交
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由 Kevin Deisz 提交于
When using PostgreSQL, it's useful to be able to specify NULLS FIRST and NULLS LAST on ordered columns. With this commit you can do that now, as in: ```ruby User.arel_table[:first_name].desc.nulls_last ```
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- 16 3月, 2019 1 次提交
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由 Ryuta Kamizono 提交于
We as Arm Treasure Data are using Optimizer Hints with a monkey patch (https://gist.github.com/kamipo/4c8539f0ce4acf85075cf5a6b0d9712e), especially in order to use `MAX_EXECUTION_TIME` (refer #31129). Example: ```ruby class Job < ApplicationRecord default_scope { optimizer_hints("MAX_EXECUTION_TIME(50000) NO_INDEX_MERGE(jobs)") } end ``` Optimizer Hints is supported not only for MySQL but also for most databases (PostgreSQL on RDS, Oracle, SQL Server, etc), it is really helpful to turn heavy queries for large scale applications.
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- 25 9月, 2018 1 次提交
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由 Vladimir Kochnev 提交于
Initially, `TOP` was introduced to support `limit` for MSSQL database. Unlike PostgreSQL/MySQL/SQLite, MSSQL does not have native `LIMIT`/`OFFSET` support. The commit adding `TOP` is 1a246f71. However, it figured out that `TOP` implementation was weak and it's not sufficient to also support `OFFSET`, then `TOP` was substituted with `ROW_NUMBER()` subquery in be48ed30. This is a well known trick in MSSQL - https://stackoverflow.com/questions/2135418/equivalent-of-limit-and-offset-for-sql-server. So now we don't need this `visit_Arel_Nodes_Top` at all. It does nothing useful but also adds an extra space after `SELECT` when `LIMIT` is being used for **any** database.
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- 24 2月, 2018 2 次提交
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由 Matthew Draper 提交于
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由 Matthew Draper 提交于
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