def build_inner_query(request, tags):
"""Build an "inner query" -- a query which yields a list of stream
ids (indexes in the stream table). These match the identifiers
used in the reading db, or can be used as part of a join. The
query performs auth checks and will check for the tags specified.
"""
# the inner query builds a list of streams matching all the
# clauses which we can then select from
clauses = []
uuid_clause = "true"
for (k, v) in tags:
if k == 'uuid':
if v != None:
uuid_clause = "s.uuid = %s" % escape_string(v)
continue
if v != None:
clauses.append("hstore(%s, %s)" % (escape_string(k),
escape_string(v)))
else: break
if len(clauses) == 0: clauses = ["hstore(array[]::varchar[])"]
inner_query = """
(SELECT s.id FROM stream s, subscription sub
WHERE s.subscription_id = sub.id AND (%s) AND (%s) AND s.metadata @> (%s))
""" % (build_authcheck(request), uuid_clause, ' || '.join(clauses))
return inner_query, clauses
def build_query(db, request, tags):
"""Will wrap a query which an appropriate selector to yield
distinct tagnames, tagvals, or uuids depending on what is needed.
"""
inner_query, clauses = build_inner_query(request, tags)
if len(tags) and tags[-1][0] == 'uuid':
# if we select uuid as the trailing tag we have to be special
query = """
SELECT DISTINCT s.uuid
FROM stream AS s
WHERE s.id IN """ + inner_query
elif len(tags) and (tags[-1][1] == None or tags[-1][1] == ''):
# odd-numbered clasues, so we print matching values of tags
t = escape_string(tags[-1][0])
query = """
SELECT DISTINCT metadata -> %s AS svals FROM stream
WHERE id IN %s AND metadata ? %s
ORDER BY svals ASC""" % (t, inner_query, t)
else:
# otherwise we print all tags matching the restriction
query = """
SELECT DISTINCT skeys
FROM (
SELECT skeys(metadata) FROM stream
WHERE id IN %s
) AS skeys ORDER BY skeys ASC""" % inner_query
log.msg(query)
d = db.runQuery(query)
d.addCallback(log_time, time.time())
return d
def build_authcheck(request, ti='', forceprivate=False):
"""Build an SQL WHERE clause which enforces access restrictions.
Will pull any credentials out of the request object passed in.
"""
if not 'private' in request.args and not forceprivate:
query = "(sub%s.public " % ti
else:
query = "(false "
if 'key' in request.args:
query += 'OR ' + ' OR '.join(["sub.key = %s" % escape_string(x + ti)
for x in request.args['key']])
query += ")"
return query
