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opt: improve query plans on tables with ascending keys #83431

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mgartner opened this issue Jun 27, 2022 · 2 comments
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opt: improve query plans on tables with ascending keys #83431

mgartner opened this issue Jun 27, 2022 · 2 comments
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@michae2
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C-enhancement Solution expected to add code/behavior + preserve backward-compat (pg compat issues are exception) T-sql-queries SQL Queries Team

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@mgartner
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mgartner commented Jun 27, 2022 •
edited by vy-ton
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This ascending query problem is a common problem for database optimizers. The problem is that the optimizer assumes that a columns has zero or very few values outside of the maximum (and minimum) values in the collected histograms. If newly inserted values are ever-increasing, then the optimizer can wildly underestimate the rows that match filters for the latest values, leading to query plans with very poor performance.

A detailed description of the problem can be found at #64570 (comment).

Jira issue: CRDB-17067

Epic: CRDB-13963
@mgartner mgartner added the C-enhancement Solution expected to add code/behavior + preserve backward-compat (pg compat issues are exception) label Jun 27, 2022
@blathers-crl blathers-crl bot added the T-sql-queries SQL Queries Team label Jun 27, 2022
@mgartner mgartner mentioned this issue Jun 27, 2022
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@mgartner mgartner mentioned this issue Jul 1, 2022
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@rytaft
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rytaft commented Jul 3, 2022

Is this a duplicate of #79872?

@mgartner
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mgartner commented Jul 5, 2022

Yes, closing.

@mgartner mgartner closed this as completed Jul 5, 2022
@mgartner mgartner moved this to Done in SQL Queries Jul 24, 2023
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