[ psqlodbc-Bugs-1010731 ] Incorrect info for varchar(255), text columns
От | |
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Тема | [ psqlodbc-Bugs-1010731 ] Incorrect info for varchar(255), text columns |
Дата | |
Msg-id | 20091118222221.E88B41072085@pgfoundry.org обсуждение исходный текст |
Список | pgsql-odbc |
Bugs item #1010731, was opened at 2009-11-18 20:55 You can respond by visiting: http://pgfoundry.org/tracker/?func=detail&atid=538&aid=1010731&group_id=1000125 Category: None Group: None Status: Open Resolution: None Priority: 3 Submitted By: Farid Zidan (faridz) Assigned to: Nobody (None) Summary: Incorrect info for varchar(255), text columns Initial Comment: PostgreSQL ANSI ODBC driver 8.04.01 returns incorrect info for SQLColAttribute SQL_DESC_TYPE and/or SQL_DESC_OCTET_LENGTH Example, create table test_varchar(col1 varchar(20), col2 varchar(255), col3 text); I get the following information from SQLColAttribute: column SQL_DESC_TYPE SQL_DESC_OCTET_LENGTH col1 SQL_VARCHAR 20 col2 SQL_LONGVARCHAR 255 col3 SQL_LONGVARCHAR 8190 col1 info is correct. col2 SQL_DESC_TYPE should be SQL_VARCHAR not SQL_LONGVARCHAR. col3 SQL_DESC_OCTET_LENGTH should be something large such as 2147483647 (2**31 -1) Attached is screenshot of the Firebird vs PostgreSQL ODBC driver results for the test table above (MS SQL Server ODBC driverreturns the same info as the Firebird ODBC driver) ---------------------------------------------------------------------- Comment By: Richard Broersma (rabroersma) Date: 2009-11-18 22:22 Message: > I suspect the limit on the long varchar size was done as > I workaround for something, in that case only people that > need the workaround should get it and everybody who does > not need it or want it by default. It I were to make a guess, I would say that these setting were defaulted so that there would be an exact mapping to the MS-Accessdata types: text{255} and memo{8190}. I would expect that there is special magic to make the data type mappings work nicely with MS SQL Server using ODBC linkedtables. I not sure how nicely Firebird ODBC driver would work when mapping data type to MS-Access. For example, try linking a table with a TEXT PRIMARY KEY (perfectly valid in PostgreSQL). While MS-Access will not allowits mapped memo data type to be assigned as a primary key. ---------------------------------------------------------------------- Comment By: Farid Zidan (faridz) Date: 2009-11-18 22:08 Message: Thanks. That is very related. I updated the driver page 1 options Max Varchar to 2000 and Max LongVarChar to 2147483647 and now I get identical results to other ODBC drivers. I understand the need to set a limit to SQL_VARCHAR buffers, the default value 254 is very small a more reasonable value is 2000 or 8190. However, setting a limit on SQL_LONGVARCHAR by default to 8190 seems to be very odd. No other driver does that. If I define a column at the Server as TEXT then I want to get all its data and not the first 8190 characters (by default). I suspect the limit on the long varchar size was done as I workaround for something, in that case only people that need the workaround should get it and everybody who does not need it or want it by default. This issue is similar to http://pgfoundry.org/tracker/? func=detail&aid=1010516&group_id=1000125&atid=538 where the driver does LF <-> LF/CR by default. I believe both are the wrong default behavior by the driver and by default the max on SQL_LONGVARCHAR column should be the same as the server supported max for the datatype TEXT (2**31 - 1) so user will not have to change anything to use the driver. OK, I need to update this issue title to say: Driver Max LongVarChar value should be the same as Server max for TEXT datatype by default, and update driver Max Varchar option to something bigger such as 2000 (like Oracle) or 8000 (like MS SQL Server), otherwise every user who wants to use the driver to handle TEXT columns bigger than 8190 will have to fiddle with the driver options which should be not required nor necessary if the driver used the server max size for the TEXT column like you expect to do ---------------------------------------------------------------------- Comment By: Richard Broersma (rabroersma) Date: 2009-11-18 21:21 Message: I have one thought that might be unrelated to your problem: Notice the ODBC driver setting for Max LongVarChar. http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/~checkout~/psqlodbc/psqlodbc/docs/config.html?rev=1.10&content-type=text/html I wonder if the ODBC driver is masking the actual size that a TEXT column could be? ---------------------------------------------------------------------- You can respond by visiting: http://pgfoundry.org/tracker/?func=detail&atid=538&aid=1010731&group_id=1000125
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