Files @ 90e06f53af8c
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Location: kallithea/rhodecode/lib/dbmigrate/migrate/changeset/databases/oracle.py

Marcin Kuzminski
Implemented cache-map on main page to save executing select
statements that checks if cache should be invalidated.
It reduces number of executed queries from N which is number of
repos to 1 which is needed to fetch all keys from database.
On pages with large number of repos this could reduce load time by half
"""
   Oracle database specific implementations of changeset classes.
"""
import sqlalchemy as sa
from sqlalchemy.databases import oracle as sa_base

from rhodecode.lib.dbmigrate.migrate import exceptions
from rhodecode.lib.dbmigrate.migrate.changeset import ansisql, SQLA_06


if not SQLA_06:
    OracleSchemaGenerator = sa_base.OracleSchemaGenerator
else:
    OracleSchemaGenerator = sa_base.OracleDDLCompiler


class OracleColumnGenerator(OracleSchemaGenerator, ansisql.ANSIColumnGenerator):
    pass


class OracleColumnDropper(ansisql.ANSIColumnDropper):
    pass


class OracleSchemaChanger(OracleSchemaGenerator, ansisql.ANSISchemaChanger):

    def get_column_specification(self, column, **kwargs):
        # Ignore the NOT NULL generated
        override_nullable = kwargs.pop('override_nullable', None)
        if override_nullable:
            orig = column.nullable
            column.nullable = True
        ret = super(OracleSchemaChanger, self).get_column_specification(
            column, **kwargs)
        if override_nullable:
            column.nullable = orig
        return ret

    def visit_column(self, delta):
        keys = delta.keys()

        if 'name' in keys:
            self._run_subvisit(delta,
                               self._visit_column_name,
                               start_alter=False)

        if len(set(('type', 'nullable', 'server_default')).intersection(keys)):
            self._run_subvisit(delta,
                               self._visit_column_change,
                               start_alter=False)

    def _visit_column_change(self, table, column, delta):
        # Oracle cannot drop a default once created, but it can set it
        # to null.  We'll do that if default=None
        # http://forums.oracle.com/forums/message.jspa?messageID=1273234#1273234
        dropdefault_hack = (column.server_default is None \
                                and 'server_default' in delta.keys())
        # Oracle apparently doesn't like it when we say "not null" if
        # the column's already not null. Fudge it, so we don't need a
        # new function
        notnull_hack = ((not column.nullable) \
                            and ('nullable' not in delta.keys()))
        # We need to specify NULL if we're removing a NOT NULL
        # constraint
        null_hack = (column.nullable and ('nullable' in delta.keys()))

        if dropdefault_hack:
            column.server_default = sa.PassiveDefault(sa.sql.null())
        if notnull_hack:
            column.nullable = True
        colspec = self.get_column_specification(column,
            override_nullable=null_hack)
        if null_hack:
            colspec += ' NULL'
        if notnull_hack:
            column.nullable = False
        if dropdefault_hack:
            column.server_default = None

        self.start_alter_table(table)
        self.append("MODIFY (")
        self.append(colspec)
        self.append(")")


class OracleConstraintCommon(object):

    def get_constraint_name(self, cons):
        # Oracle constraints can't guess their name like other DBs
        if not cons.name:
            raise exceptions.NotSupportedError(
                "Oracle constraint names must be explicitly stated")
        return cons.name


class OracleConstraintGenerator(OracleConstraintCommon,
                                ansisql.ANSIConstraintGenerator):
    pass


class OracleConstraintDropper(OracleConstraintCommon,
                              ansisql.ANSIConstraintDropper):
    pass


class OracleDialect(ansisql.ANSIDialect):
    columngenerator = OracleColumnGenerator
    columndropper = OracleColumnDropper
    schemachanger = OracleSchemaChanger
    constraintgenerator = OracleConstraintGenerator
    constraintdropper = OracleConstraintDropper