def process_linkprop_update(ir_stmt: irast.MutatingStmt, ir_expr: irast.Base,
wrapper: pgast.Query,
dml_cte: pgast.CommonTableExpr, *,
ctx: context.CompilerContextLevel) -> None:
"""Perform link property updates to a link relation.
:param ir_stmt:
IR of the statement.
:param ir_expr:
IR of the UPDATE body element.
:param wrapper:
Top-level SQL query.
:param dml_cte:
CTE representing the SQL UPDATE to the main relation of the Object.
"""
toplevel = ctx.toplevel_stmt
rptr = ir_expr.rptr
ptrcls = rptr.ptrcls
target_tab = dbobj.range_for_ptrcls(ptrcls,
'>',
include_overlays=False,
env=ctx.env)
dml_cte_rvar = pgast.RangeVar(
relation=dml_cte,
alias=pgast.Alias(aliasname=ctx.env.aliases.get('m')))
cond = astutils.new_binop(
pathctx.get_rvar_path_identity_var(dml_cte_rvar,
ir_stmt.subject.path_id,
env=ctx.env),
dbobj.get_column(target_tab, 'source', nullable=False),
op='=',
)
targets = []
for prop_el in ir_expr.shape:
ptrname = prop_el.rptr.ptrcls.get_shortname(ctx.env.schema)
with ctx.new() as input_rel_ctx:
input_rel_ctx.expr_exposed = False
input_rel = dispatch.compile(prop_el.expr, ctx=input_rel_ctx)
targets.append(pgast.UpdateTarget(name=ptrname.name,
val=input_rel))
updstmt = pgast.UpdateStmt(relation=target_tab,
where_clause=cond,
targets=targets,
from_clause=[dml_cte_rvar])
updcte = pgast.CommonTableExpr(
query=updstmt,
name=ctx.env.aliases.get(ptrcls.get_shortname(ctx.env.schema).name))
toplevel.ctes.append(updcte)
def process_update_body(ir_stmt: irast.MutatingStmt, wrapper: pgast.Query,
update_cte: pgast.CommonTableExpr,
range_cte: pgast.CommonTableExpr, *,
ctx: context.CompilerContextLevel):
"""Generate SQL DML CTEs from an UpdateStmt IR.
:param ir_stmt:
IR of the statement.
:param wrapper:
Top-level SQL query.
:param update_cte:
CTE representing the SQL UPDATE to the main relation of the Object.
:param range_cte:
CTE representing the range affected by the statement.
"""
update_stmt = update_cte.query
external_updates = []
toplevel = ctx.toplevel_stmt
toplevel.ctes.append(range_cte)
toplevel.ctes.append(update_cte)
with ctx.newscope() as subctx:
# It is necessary to process the expressions in
# the UpdateStmt shape body in the context of the
# UPDATE statement so that references to the current
# values of the updated object are resolved correctly.
subctx.path_scope[ir_stmt.subject.path_id] = update_stmt
subctx.rel = update_stmt
subctx.expr_exposed = False
subctx.shape_format = context.ShapeFormat.FLAT
for shape_el in ir_stmt.subject.shape:
with subctx.newscope() as scopectx:
ptrcls = shape_el.rptr.ptrcls
updvalue = shape_el.expr
ptr_info = pg_types.get_pointer_storage_info(
ptrcls,
schema=scopectx.env.schema,
resolve_type=True,
link_bias=False)
# First, process all internal link updates
if ptr_info.table_type == 'ObjectType':
updvalue = pgast.TypeCast(
arg=dispatch.compile(updvalue, ctx=scopectx),
type_name=typecomp.type_node(ptr_info.column_type))
update_stmt.targets.append(
pgast.UpdateTarget(name=ptr_info.column_name,
val=updvalue))
props_only = is_props_only_update(shape_el)
ptr_info = pg_types.get_pointer_storage_info(ptrcls,
resolve_type=False,
link_bias=True)
if ptr_info and ptr_info.table_type == 'link':
external_updates.append((shape_el, props_only))
if not update_stmt.targets:
# No updates directly to the set target table,
# so convert the UPDATE statement into a SELECT.
update_cte.query = pgast.SelectStmt(
ctes=update_stmt.ctes,
target_list=update_stmt.returning_list,
from_clause=[update_stmt.relation] + update_stmt.from_clause,
where_clause=update_stmt.where_clause,
path_namespace=update_stmt.path_namespace,
path_outputs=update_stmt.path_outputs,
path_scope=update_stmt.path_scope,
path_rvar_map=update_stmt.path_rvar_map.copy(),
view_path_id_map=update_stmt.view_path_id_map.copy(),
ptr_join_map=update_stmt.ptr_join_map.copy(),
)
# Process necessary updates to the link tables.
for expr, props_only in external_updates:
if props_only:
process_linkprop_update(ir_stmt,
expr,
wrapper,
update_cte,
ctx=ctx)
else:
process_link_update(ir_stmt,
expr,
False,
wrapper,
update_cte,
None,
ctx=ctx)
