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Re: n_live_tup number double after migration do PG 10.4 - Mailing list pgsql-admin

From Keith
Subject Re: n_live_tup number double after migration do PG 10.4
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Msg-id CAHw75vtv6TuXK88K3+YoVW903YCaTSSb+StONafdAMEsSrhCKQ@mail.gmail.com
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In response to n_live_tup number double after migration do PG 10.4  (Mai Peng <maily.peng@webedia-group.com>)
Responses Re: n_live_tup number double after migration do PG 10.4  (Tom Lane <tgl@sss.pgh.pa.us>)
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On Sun, Aug 5, 2018 at 5:29 AM, Mai Peng <maily.peng@webedia-group.com> wrote:
Hi all,

After the migration to pg 10 by pg_upgrade and vacuumdb, I’ve seen the number of live tuple double and performance decreases on few queries.
Where do these live tuples coming from ?

Thank you

The value stored in n_liv_tup is the value seen when the last analyze was run on the table. It is not kept up to date on every row change and only changes when an analyze is run again. So perhaps the tables you're referencing hadn't been analyzed for a while before you upgraded?

Keith

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