Re: Moving Database Cluster to another drive

Thank Luca,

You wrote that "each index has a pointer to the block on disk that contains the tuple". If there is no mechanism that insure the tuples have the same location on the new drive (the block address), I should then expect a plane copy will corrupt some/all the indexes, am I right (linked to the second question)?

Best regards,
Daniel

-----Original Message-----
From: pgsql-novice-owner(at)postgresql(dot)org [mailto:pgsql-novice-owner(at)postgresql(dot)org] On Behalf Of Luca Ferrari
Sent: May-18-15 02:27
To: Daniel Begin
Cc: pgsql-novice(at)postgresql(dot)org
Subject: Re: [NOVICE] Moving Database Cluster to another drive

On Sat, May 16, 2015 at 7:39 PM, Daniel Begin <jfd553(at)hotmail(dot)com> wrote:
> - How indexes are actually implemented in PostgreSQL (how pgsql point
> to a record from an index)?
>

Not an easy answer. An index can have different implementation types, but for short each index has a pointer to the block on disk that contain the tuple. And indexes are, of course, on disk stuff.

> - Could copying tables and indexes have had an effect on indexes?
>

Should not, but it could be.

> - How can I verify that some of the indexes were not corrupted?
>

Use explain, see pg_stat_user_indexes and do a reindex if you believe an index is corrupted.

I would expect this being more likely an issue with the hard drive (e.g., different seek times from the previous one).

Luca

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