Horton

Re: Parallel copy

vignesh C <vignesh21@gmail.com>

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From: vignesh C <vignesh21@gmail.com>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2020-11-18T10:12:43Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Allow WaitLatch() to be used without a latch.

  2. Add %P to log_line_prefix for parallel group leader

  3. Include replication origins in SQL functions for commit timestamp

  4. Avoid useless buffer allocations during binary COPY FROM.

On Sat, Oct 31, 2020 at 2:07 AM Tomas Vondra <tomas.vondra@2ndquadrant.com>
wrote:
>
> Hi,
>
> I've done a bit more testing today, and I think the parsing is busted in
> some way. Consider this:
>
>      test=# create extension random;
>      CREATE EXTENSION
>
>      test=# create table t (a text);
>      CREATE TABLE
>
>      test=# insert into t select random_string(random_int(10, 256*1024))
from generate_series(1,10000);
>      INSERT 0 10000
>
>      test=# copy t to '/mnt/data/t.csv';
>      COPY 10000
>
>      test=# truncate t;
>      TRUNCATE TABLE
>
>      test=# copy t from '/mnt/data/t.csv';
>      COPY 10000
>
>      test=# truncate t;
>      TRUNCATE TABLE
>
>      test=# copy t from '/mnt/data/t.csv' with (parallel 2);
>      ERROR:  invalid byte sequence for encoding "UTF8": 0x00
>      CONTEXT:  COPY t, line 485: "m&\nh%_a"%r]>qtCl:Q5ltvF~;2oS6@HB
>F>og,bD$Lw'nZY\tYl#BH\t{(j~ryoZ08"SGU~.}8CcTRk1\ts$@U3szCC+U1U3i@P..."
>      parallel worker
>
>
> The functions come from an extension I use to generate random data, I've
> pushed it to github [1]. The random_string() generates a random string
> with ASCII characters, symbols and a couple special characters (\r\n\t).
> The intent was to try loading data where a fields may span multiple 64kB
> blocks and may contain newlines etc.
>
> The non-parallel copy works fine, the parallel one fails. I haven't
> investigated the details, but I guess it gets confused about where a
> string starts/end, or something like that.
>

Thanks for identifying this issue, this issue is fixed in v10 patch posted
at [1]
[1]
https://www.postgresql.org/message-id/CALDaNm05FnA-ePvYV_t2%2BWE_tXJymbfPwnm%2Bkc9y1iMkR%2BNbUg%40mail.gmail.com


Regards,
Vignesh
EnterpriseDB: http://www.enterprisedb.com