Overview

The Delete_Returning deletes rows from a given table. Every row provided by the input operator is sent to the StoreAdapter#deleteRow() method to be removed from the table.

Arguments

input: the input operator supplying rows to be deleted.

Behaviour

Rows supplied by the input operator are deleted from the underlying data store through the StoreAdapter interface.

Output

The rows deleted are returned through the cursor interface.

Assumptions

The rows provided by the input operator includes all of the columns for the HKEY to allow the persistit layer to lookup the row in the btree to remove it. Failure results in a RowNotFoundException being thrown and the operation aborted. The operator assumes (but does not require) that all rows provided are of the same RowType. The Delete_Returning operator assumes (and requires) the input row types be of a TableRowType, and not any derived type. This can't be enforced by the constructor because PhysicalOperator#rowType() isn't implemented for all operators.

Performance

Deletion assumes the data store needs to alter the underlying storage system, including any system change log. This requires multiple IOs per operation.

Memory Requirements

Each row is individually processed.

                StoreAdapter adapter = givenStore.createAdapter(session, SchemaCache.globalSchema(newAIS));
                CreateAsCompiler compiler = new CreateAsCompiler(server, adapter, true, newAIS);
                PlanContext planContext = new PlanContext(compiler);
                BasePlannable insertResult = compiler.compile((DMLStatementNode) insertStmt, null, planContext);
                insertPlan = insertResult.getPlannable();
                deletePlan = new Delete_Returning(insertPlan.getInputOperators().iterator().next(), false);
            }
            int tableID = cs.getTableId();
            TableRowType newType = newSchema.tableRowType(tableID);
            TableTransform transform = buildTableTransform(cs, changeLevel, oldAIS, newType, typesRegistry,
                                                typesTranslator, (Operator)deletePlan, (Operator)insertPlan);

Examples of com.foundationdb.qp.operator.Delete_Returning