Re: range test for hash index?

From: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
To: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
Cc: Paul A Jungwirth <pj(at)illuminatedcomputing(dot)com>, Jeff Davis <pgsql(at)j-davis(dot)com>, Heikki Linnakangas <heikki(dot)linnakangas(at)iki(dot)fi>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: range test for hash index?
Date: 2019-09-26 22:33:33
Message-ID: 20190926223333.gll24ohrie7a5cki@development
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On Wed, Sep 25, 2019 at 09:07:13AM +0530, Amit Kapila wrote:
>On Wed, Sep 18, 2019 at 9:30 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> On Mon, Sep 16, 2019 at 11:24 PM Paul A Jungwirth
>> <pj(at)illuminatedcomputing(dot)com> wrote:
>> >
>> > On Mon, Sep 16, 2019 at 5:28 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> > > I don't see this function on the master branch. Is this function name
>> > > correct? Are you looking at some different branch?
>> >
>> > Sorry about that! You're right, I was on my multirange branch. But I
>> > see the same thing on latest master (but calling hash_range instead of
>> > hash_range_internal).
>> >
>> No problem, attached is a patch with a proposed commit message. I
>> will wait for a few days to see if Heikki/Jeff or anyone else responds
>> back, otherwise will commit and backpatch this early next week.
>Today, while I was trying to backpatch, I realized that hash indexes
>were not WAL-logged before 10 and they give warning "WARNING: hash
>indexes are not WAL-logged and their use is discouraged". However,
>this test has nothing to do with the durability of hash-indexes, so I
>think we can safely backpatch, but still, I thought it is better to
>check if anybody thinks that is not a good idea. In back-branches,
>we are already using hash-index in regression tests in some cases like
>enum.sql, macaddr.sql, etc., so adding for one more genuine case
>should be fine. OTOH, we can back-patch till 10, but the drawback is
>the tests will be inconsistent across branches. Does anyone think it
>is not a good idea to backpatch this till 9.4?

By "inconsistent" you mean that pre-10 versions will have different
expected output than versions with WAL-logged hash indexes? I don't see
why that would be a reason not to backpatch to all supported versions,
considering we already have the same difference for other test suites.


Tomas Vondra
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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