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Generate proper error for UNION DISTINCT with more than 255 columns [CORE6205] #6450

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firebird-automations opened this issue Dec 11, 2019 · 11 comments

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@firebird-automations
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Submitted by: Jan Kohlmeyer (colaflasche)

Votes: 1

Hi,

I have a union with 256 or more columns and recive this error, if I execute this:
Invalid token.
invalid request BLR at offset 5668.
BLR syntax error: expected record selection expression clause at offset 5669, encountered 24.

If I change to a union all, there is no Problem:

select
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256
from rdb$database

union --all

select
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256
from rdb$database

Commits: 0f6c5b5

@firebird-automations
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Modified by: @asfernandes

assignee: Adriano dos Santos Fernandes [ asfernandes ]

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Modified by: @asfernandes

summary: union distinct with more then 255 Columns => Generate proper error for UNION DISTINCT with more than 255 columns

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Commented by: @asfernandes

The fix consist of generation of proper error message.

There is an implementation restriction for that, like with DISTINCT, ORDER BY and GROUP BY.

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Modified by: @asfernandes

status: Open [ 1 ] => Resolved [ 5 ]

resolution: Fixed [ 1 ]

Fix Version: 4.0 Beta 2 [ 10888 ]

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Commented by: @livius2

Adriano,
can you describe more details about this limit?

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Commented by: @asfernandes

Sort is limited by 255 items, all these clauses need sort.

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Commented by: @livius2

Yes i saw this in your commit comments but why it is limited to 255 items?

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Commented by: Sean Leyne (seanleyne)

There are numerous places in the code where the implementation was/is limited to 255 (type = WORD):
- number of "stream"/table references in a SELECT
- number of columns in a ORDER BY/GROUP BY
- number of tables formats
- {there could be others that aren't coming to mind ATM}

the limitations are from way back, before the project existed.

IMO, the limits are reasonable

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Commented by: @livius2

Sean, thank you for the info.

>> 255 (type = WORD)

WORD or BYTE?

>> the limits are reasonable
Some yes, others not.
Table formats, on production server yes on dev maybe too.
Order by - yes.
Group by - probably, as near to always it contain many fields to retrive only value not aggregate and can be revritten to derived table +join
But union/distinct - no it is not. Good that i have max here 192 fields in union/distinct.
Will be good to include this info in Firebird limits page.

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Modified by: @pavel-zotov

status: Resolved [ 5 ] => Resolved [ 5 ]

QA Status: No test => Done successfully

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Modified by: @pavel-zotov

status: Resolved [ 5 ] => Closed [ 6 ]

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