Thread: what happens when concurrent index create

i read documents,i find it that concurrent index create don't lock write.but
need scan table twice.it explain is following as:
   It scans the table once to initially build the index, then makes a second
pass to look for things added after the first pass.

please explain 1. what happens  when concurrent index create .tks.
                   2.how to trace a backend what do somethings internal.for
example oracle 10046 trace.

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leo xu wrote:
> i read documents,i find it that concurrent index create don't lock
write.but
> need scan table twice.it explain is following as:
>    It scans the table once to initially build the index, then makes a
second
> pass to look for things added after the first pass.
>
> please explain 1. what happens  when concurrent index create .tks.

You quoted the explanation above...
If you need to know more, read the source: it is the function
DefineIndex
in src/backend/commands/indexcmds.c


>                    2.how to trace a backend what do somethings
internal.for
> example oracle 10046 trace.

SET log_min_messages=DEBUG5;

Then do what you want logged.  Afterwards read the log file.

You need to be superuser for this command.  If you want to switch
to a regular user after issuing the command, say

SET SESSION AUTHORIZATION some_user;

Yours,
Laurenz Albe