Once you enable compatibility mode, Adaptive Server uses the query processor for all insert, delete, update, and select queries.
The query processor uses either full or partial compatibility mode:
Full compatibility mode – Adaptive Server 15.0 uses an optimization and execution strategy similar to the one used in version 12.5.x.
Restricted compatibility mode – Adaptive Server uses only an optimization strategy similar to the one used in version 12.5.x.
Generally, Adaptive Server uses full compatibility mode wherever possible. If it cannot use full compatibility mode, it switches to restricted compatibility mode.
Table 3-1 lists restricted compatibility mode support for features in Adaptive Server versions earlier than 15.0:
12.5.4 features with limited support in compatibility mode |
Supported in full compatibility mode? |
Supported in restricted compatibility mode? |
|---|---|---|
Queries with text and image columns |
No |
Yes |
Referential integrity |
No |
Yes |
Inserts that require referential integrity |
No |
No |
Proxy tables |
No |
Yes |
Round-robin partitions |
No |
No |
Encryption and cipher text |
No |
Yes |
Queries that include the rand2 function |
No |
Yes |
Abstract plans, either explicit (with plan clause) or implicit (plan dump or plan load); |
No |
Yes |
Extended datatypes, such as Java ADT and Java UDF |
No |
Yes |
XML functions |
No |
Yes |
Browse mode |
No |
Yes |
Parallel hints |
No |
No |
Parallel sort |
No |
No |
Compatibility mode does not support these Adaptive Server 15.0 features:
Partitioned tables
group bys with more than 31 columns
Scrollable and insensitive cursors
Commands on computed columns
Queries that fire “instead-of-triggers”
Queries executed inside “instead-of-triggers”
Queries that issue parameterized literals in the statement cache, unless the query includes an insert...values command
Query processing diagnostics used by showplan_in_xml
Queries that include hash or hashbyte functions
User-defined functions (SQL UDFs)
Explicit timestamp inserts (available for Adaptive Server version 15.0.2 and later and in Replication Server®)
SQL-based replication (available for Adaptive Server version 15.0.3 and later)
group by result rows that are wider than the maximum size that fits on a data page
xmltable function
Query plans in compatibility mode are not executed as
parallel plans.
