[#CORE-4881] Increase maximum string literal length to 64K (bytes) while setting a lower limit (of characters) for multibyte charsets based on their max char. length (UTF-8 literals will be limited to 16383 characters)

Firebird Core

Increase maximum string literal length to 64K (bytes) while setting a lower limit (of characters) for multibyte charsets based on their max char. length (UTF-8 literals will be limited to 16383 characters)

Created: 22/Jul/15 03:18 PM Updated: 04/Aug/15 02:53 PM

Component/s:

Engine

Affects Version/s:

None

Fix Version/s:

3.0 RC1

QA Status:

Done successfully

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Pavel Zotov added a comment - 30/Jul/15 06:07 PM

Can anyone explain me please why following script:

script-1:
######

set names utf8; ----------------------------- [ 1 ]
create database 'localhost/3333:C:\MIX\firebird\QA\fbt-repo\tmp\c4881.fdb' default character set utf8;

set planonly;
set sqlda_display on;
select _octets ' . . .literal string containing ONLY ascii characters with total length = 65535 bytes ...' as ascii_only
from rdb$database;

-- produces:
==========

OUTPUT message field count: 1
01: sqltype: 452 TEXT scale: 0 subtype: 0 len: 32767 charset: 1 OCTETS
  : name: CONSTANT alias: ASCII_ONLY
  : table: owner:

And this:

script-2:
######

set names NONE; --------------------------- [ 2 ]
create database 'localhost/3333:C:\MIX\firebird\QA\fbt-repo\tmp\c4881.fdb' default character set utf8;

// ... the rest is the same as in script-1 ...

-- produces:
==========

OUTPUT message field count: 1
01: sqltype: 452 TEXT scale: 0 subtype: 0 len: 65533 charset: 1 OCTETS
  : name: CONSTANT alias: ASCII_ONLY
  : table: owner:

From where values '32767' and '65533' come ?

1) If connection charset is UTF8 than is is possible to create literals that will use MORE than two bytes for encoding (in practice one may easy to create literals with 3 bpc; I could not create with 4 bytes, but this seems due to my poor windows)
So, value '32767' is wrong, it should be floor( 65535 / 4 ), isn't ?

2) from where 65533 rather than 65535 for second test ?

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Adriano dos Santos Fernandes added a comment - 04/Aug/15 02:53 PM

select _octets ' . . .literal string containing ONLY ascii characters with total length = 65535 bytes ...' as ascii_only
from rdb$database;

Produces sqllen = 65533 (not the value you said) because internally it's converted to varchar and that is the max. That will cause a runtime error.