When does sequential performance matter in PG?

From: henk de wit
Subject: When does sequential performance matter in PG?
Date: ,
Msg-id: COL104-W4301D2DDC445A99E55E086F5A10@phx.gbl
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Responses: Re: When does sequential performance matter in PG?  (Matthew Wakeling)
Re: When does sequential performance matter in PG?  (Greg Smith)
List: pgsql-performance

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When does sequential performance matter in PG?  (henk de wit, )
 Re: When does sequential performance matter in PG?  (Matthew Wakeling, )
  Re: When does sequential performance matter in PG?  (henk de wit, )
  Re: When does sequential performance matter in PG?  (Scott Carey, )
 Re: When does sequential performance matter in PG?  (Greg Smith, )

Hi,

It is frequently said that for PostgreSQL the number 1 thing to pay attention to when increasing performance is the amount of IOPS a storage system is capable of. Now I wonder if there is any situation in which sequential IO performance comes into play. E.g. perhaps during a tablescan on a non-fragmented table, or during a backup or restore?

The reason I'm asking is that we're building a storage array and for some reason are unable to increase the number of random IOPS beyond a certain threshold when we add more controllers or more (SSD) disks to the system. However, the sequential performance keeps increasing when we do that.

Would this extra sequential performance be of any benefit to PG or would it just be wasted?

Kind regards


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From: Scott Carey
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Subject: Re: When does sequential performance matter in PG?
From: "Steve McLellan"
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Subject: Query performance over a large proportion of data