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#         http://www.apache.org/licenses/LICENSE-2.0
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from sqlalchemy import Index, MetaData, Table


TABLE_NAME = 'compute_node_stats'
IDX_NAME = 'compute_node_stats_node_id_and_deleted_idx'


def upgrade(migrate_engine):
    """Add an index to make the scheduler lookups of compute_nodes and joined
    compute_node_stats more efficient.
    """
    meta = MetaData(bind=migrate_engine)
    cn_stats = Table(TABLE_NAME, meta, autoload=True)
    idx = Index(IDX_NAME, cn_stats.c.compute_node_id, cn_stats.c.deleted)
    idx.create(migrate_engine)


def downgrade(migrate_engine):
    meta = MetaData(bind=migrate_engine)
    cn_stats = Table(TABLE_NAME, meta, autoload=True)
    idx = Index(IDX_NAME, cn_stats.c.compute_node_id, cn_stats.c.deleted)
    idx.drop(migrate_engine)

Add an index to compute_node_stats
Add an index to compute_node_stats

This will improve the performance of scheduler lookups of compute nodes
and their associated stats.

bug 1177487

Change-Id: I0e04849543916e874ea0ddfc76c3d70ff71c09d0
