Gpre Migration Issues
SQLDA :
6.0 gpre will only support XSQLDA structures. The support for old style
SQLDA is removed. This means that old gpre applications that used SQLDA has to
be re-written using XSQLDA. The three main steps involved in doing this are :
- Replace SQLDA with XSQLDA in variable definitions.
i.e. SQLDA *input, *output; will become XSQLDA *input,
*output
- Use XSQLDA_LENGTH macro to calculate the XSQLDA variable's length.
. i.e. input=(XSQLDA*) malloc
(XSQLDA_LENGTH(4));
- Set the sqlda version as 1
i.e. input->version=SQLDA_VERSION1;
SQL Date, Time,
Timestamp:
InterBase 6.0 gpre allows the user to exploit the new datatype i.e. date,
time, timestamp present in 6.0 server. This also means that in order to support
backward compatability gpre would have to emit proper definitions, blr and dyn
depending upon the database ods, server version and sql dialect when
pre-processing a esql program file.
Metadata Statements:
While creating tables, domains, procedures etc. gpre generates dyn based on
the following criteria:
- if a column type is TIMESTAMP then irrespective of the database ods, server
version, sql dialect gpre will generate dyn that represents timestamp.
- if a column type is TIME then gpre will punt with error for ods <10 and
server version < 6.0 irrespective of the dialect. For all other cases dyn
that represents sql time will be generated.
- if a column type is DATE and the ods is < 10 and server version <=6.0
then gpre will generate:
dyn that represents timestamp if the sql dialect is 1
Error if the sql dialect is 2,3
- For all other cases i.e. ods is==10 and server==6.0 gpre will generate:
dyn that represents timestamp if the sql dialect is 1
Error if the sql dialect is 2
dyn that represents sql date if the sql dialect is 3
Data Retrieval statements:
While selecting, inserting etc. data, gpre will generate blr exactly as
specified in the criteria above. blr_timestamp, blr_sql_date, blr_sql_time will
be generated for column whose datatypes are TIMESTAMP(or DATE in dialect 1),
DATE, TIME respectively.
For a variable that is declared as based on a table column, the following
changes will be noted.
- A variable that is based on a timestamp column will be declared as
ISC_TIMESTAMP variable.
- A variable that is based on a time column will be declared as ISC_TIME
variable.
- A variable that is based on a date column will be declared as ISC_TIMESTAMP
variable in dialect 1 or as ISC_DATE variable in dialect 3.
Note that earlier versions of gpre generated ISC_QUAD for variables based on
date column type.
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