Re: A bug when use get_bit() function for a long bytea string - Mailing list pgsql-hackers
| From | movead.li@highgo.ca |
|---|---|
| Subject | Re: A bug when use get_bit() function for a long bytea string |
| Date | |
| Msg-id | 2020032817093521193529@highgo.ca Whole thread Raw |
| In response to | A bug when use get_bit() function for a long bytea string ("movead.li@highgo.ca" <movead.li@highgo.ca>) |
| Responses |
Re: A bug when use get_bit() function for a long bytea string
(Ashutosh Bapat <ashutosh.bapat@2ndquadrant.com>)
|
| List | pgsql-hackers |
I want to resent the mail, because last one is in wrong format and hardly to read.In addition, I think 'Size' or 'size_t' is rely on platform, they may can't work on 32bitsystem. So I choose 'int64' after ashutosh's review.>>I think the second argument indicates the bit position, which would be max bytea length * 8. If max bytea length covers whole int32, the second argument >needs to be wider i.e. int64.>Yes, it makes sence and followed.
>>I think we need a similar change in byteaGetBit() and byteaSetBit() as well.
Sorry, I think it's my mistake, it is the two functions above should be changed.
>>Some more comments on the patch>> struct pg_encoding>> {>>- unsigned (*encode_len) (const char *data, unsigned dlen);>>+ int64 (*encode_len) (const char *data, unsigned dlen);>> unsigned (*decode_len) (const char *data, unsigned dlen);>> unsigned (*encode) (const char *data, unsigned dlen, char *res);>> unsigned (*decode) (const char *data, unsigned dlen, char *res);>> Why not use return type of int64 for rest of the functions here as well?>> res = enc->encode(VARDATA_ANY(data), datalen, VARDATA(result));>> /* Make this FATAL 'cause we've trodden on memory ... */>>- if (res > resultlen)>>+ if ((int64)res > resultlen)>>
>>if we change return type of all those functions to int64, we won't need this cast.>I change the 'encode' function, it needs an int64 return type, but keep other
>functions in 'pg_encoding', because I think it of no necessary reason.
>>Ok, let's leave it for a committer to decide.
Well, I change all of them this time, because Tom Lane supports on next mail.
>Some more review comments.
>+ int64 res,resultlen;
>We need those on separate lines, possibly.
>We need those on separate lines, possibly.
Done
>+ byteNo = (int32)(n / BITS_PER_BYTE);
>Does it hurt to have byteNo as int64 so as to avoid a cast. Otherwise, please
>add a comment explaining the reason for the cast. The comment applies at other
>places where this change appears.
>- int len;
>+ int64 len;
>Why do we need this change?
> int i;
It is my mistake as describe above, it should not be 'bitgetbit()/bitsetbit()' to be changed.
>>It might help to add a test where we could pass the second argument something
>>greater than 1G. But it may be difficult to write such a test case.>Add two test cases.
>+
>+select get_bit(
>+ set_bit((repeat('Postgres', 512 * 1024 * 1024 / 8))::bytea, 1024 * 1024 * 1024 + 1, 0)
>+ ,1024 * 1024 * 1024 + 1);
>This bit position is still within int4.
>postgres=# select pg_column_size(1024 * 1024 * 1024 + 1);
> pg_column_size
>----------------
> 4
>(1 row)
>You want something like
>postgres=# select pg_column_size(512::bigint * 1024 * 1024 * 8);
> pg_column_size
>----------------
> 8
>(1 row)
I intend to test size large then 1G, and now I think you give a better idea and followed.
Highgo Software (Canada/China/Pakistan)
URL : www.highgo.ca
EMAIL: mailto:movead(dot)li(at)highgo(dot)ca
URL : www.highgo.ca
EMAIL: mailto:movead(dot)li(at)highgo(dot)ca
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