The enums exposed by the connector are not intended to be used by the
users of the library. The fact that the protocol, and other, modules used
it was in violation of how the library is intended to be used.
Adding an internal mapping into MaxScale also removes some of the
dependencies that the core has on the connector.
Basically it would be trivial to report far more operations
explicitly, but for the fact that the values in qc_query_op_t
currently, quite unnecessarily, form a bitmask.
In 2.2 that is no longer the case, so other operations will be
added there.
With this change, for a statement like
SELECT t2.a FROM t1 t2;
the affected field is reported as t1.a and not as t2.a, as it
was before.
For a statement like
SELECT t.f FROM d.t;
qc_mysqlembedded will now return "d.t.f" as the affected field,
while qc_sqlite will still return "t.f" as both implementations did
before. In qc_mysqlembedded's case that is a side-effect of the
alias handling. To get qc_sqlite to return the same (which would
be good), the table names would have to be collected in a smarter
way than they are now.
If a particular table appears in a statement multiple times,
qc_get_table_names will report it as many times as it appears.
Each name should be reported just once. Same applies for
database names.
- Fields in CTEs are marked as being used in subselects.
- In qc_mysqlembedded all selects must be walked if CTE is present.
- In qc_sqlite unions need special handling.
The default sql mode must now be provided explicitly when the query
classifier is setup. This is in preparation for "sql_mode" becoming
a global configuration parameter of MaxScale.
Both 10.3 and Oracle support sequence pseudo colums and corresponding
functions. Getting the next number in the sequence is in both cases
obtained using nextval/nextval() but the current number is in Oracle
obtained using currval/currval() and in 10.3 using lastval/lastval().
These fields/functions are now ignored, in the sense that they will
not show up in the field/function infos. However, they will cause the
type mask of the statement to contain the bit QUERY_TYPE_WRITE so that
statements accessing the sequence will always be sent to the master.
When developing the oracle related parser extensions, it makes
things simpler if also qc_mysqlembedded properly reports when
it cannot parse a statement.
Note, although this change is marked for 2.1, it will not be
merged into the first 2.1 GA release.
EXPLAIN statements are no longer parsed completely as doing so makes
it hard to modify the grammar for the needs or Oracle SQL.
Consequently, for an EXPLAIN statement you now bascially only get the
type and the operation (the newly added QUERY_OP_EXPLAIN and QUERY_OP_SHOW).
The other information is not interesting and is related to
information_schema and similar tables.
Changed the query operation enum to contain implicit enum values instead
of providing. The operation was never used as a bitmask so it is pointless
to declare them as such.
Added the EXECUTE type to the enum and used it in qc_sqlite and
qc_mysqlembedded.
It is now possible to specify what information the caller is interested
in. With this the cost for collecting information during the query parsing
that nobody is interested in can be avoided.
The static capabilities declared in getCapabilities allows certain
capabilities to be queried before instances are created. The intended use
of this capability is to remove the need for the `is_internal_service`
function.
The embedded parser is not capable of parsing preparable statements
containing ?:s as ordinary statements, so they have to be replaced
with something else. Replacing them with a dummy variable cannot be
done as that will affect the type of the statement. Replacing with
0 seems to be a good compromise.
