def apply_volatility_ref(stmt: pgast.SelectStmt, *,
ctx: context.CompilerContextLevel) -> None:
for ref in ctx.volatility_ref:
# Apply the volatility reference.
# See the comment in process_set_as_subquery().
stmt.where_clause = astutils.extend_binop(
stmt.where_clause, pgast.NullTest(
arg=ref(),
negated=True,
))
def anti_join(
lhs: pgast.SelectStmt,
rhs: pgast.SelectStmt,
path_id: Optional[irast.PathId],
*,
ctx: context.CompilerContextLevel,
) -> None:
"""Filter elements out of the LHS that appear on the RHS"""
if path_id:
# grab the identity from the LHS and do an
# anti-join against the RHS.
src_ref = pathctx.get_path_identity_var(lhs,
path_id=path_id,
env=ctx.env)
pathctx.get_path_identity_output(rhs, path_id=path_id, env=ctx.env)
cond_expr: pgast.BaseExpr = astutils.new_binop(src_ref, rhs, 'NOT IN')
else:
# No path we care about. Just check existance.
cond_expr = pgast.SubLink(type=pgast.SubLinkType.NOT_EXISTS, expr=rhs)
lhs.where_clause = astutils.extend_binop(lhs.where_clause, cond_expr)
def semi_join(stmt: pgast.SelectStmt, ir_set: irast.Set,
src_rvar: pgast.PathRangeVar, *,
ctx: context.CompilerContextLevel) -> pgast.PathRangeVar:
"""Join an IR Set using semi-join."""
rptr = ir_set.rptr
assert rptr is not None
# Target set range.
set_rvar = new_root_rvar(ir_set, ctx=ctx)
ptrref = rptr.ptrref
ptr_info = pg_types.get_ptrref_storage_info(ptrref,
resolve_type=False,
allow_missing=True)
if ptr_info and ptr_info.table_type == 'ObjectType':
if irtyputils.is_inbound_ptrref(ptrref):
far_pid = ir_set.path_id.src_path()
assert far_pid is not None
else:
far_pid = ir_set.path_id
else:
far_pid = ir_set.path_id
# Link range.
map_rvar = new_pointer_rvar(rptr, src_rvar=src_rvar, ctx=ctx)
include_rvar(ctx.rel,
map_rvar,
path_id=ir_set.path_id.ptr_path(),
ctx=ctx)
tgt_ref = pathctx.get_rvar_path_identity_var(set_rvar,
far_pid,
env=ctx.env)
pathctx.get_path_identity_output(ctx.rel, far_pid, env=ctx.env)
cond = astutils.new_binop(tgt_ref, ctx.rel, 'IN')
stmt.where_clause = astutils.extend_binop(stmt.where_clause, cond)
return set_rvar
def rel_join(query: pgast.SelectStmt, right_rvar: pgast.PathRangeVar, *,
ctx: context.CompilerContextLevel) -> None:
condition = None
for path_id in right_rvar.query.path_scope:
lref = maybe_get_path_var(query, path_id, aspect='identity', ctx=ctx)
if lref is None:
lref = maybe_get_path_var(query, path_id, aspect='value', ctx=ctx)
if lref is None:
continue
rref = pathctx.get_rvar_path_identity_var(right_rvar,
path_id,
env=ctx.env)
assert isinstance(lref, pgast.ColumnRef)
assert isinstance(rref, pgast.ColumnRef)
path_cond = astutils.join_condition(lref, rref)
condition = astutils.extend_binop(condition, path_cond)
if condition is None:
join_type = 'cross'
else:
join_type = 'inner'
if not query.from_clause:
query.from_clause.append(right_rvar)
if condition is not None:
query.where_clause = astutils.extend_binop(query.where_clause,
condition)
else:
larg = query.from_clause[0]
rarg = right_rvar
query.from_clause[0] = pgast.JoinExpr(type=join_type,
larg=larg,
rarg=rarg,
quals=condition)
