Cloning utility functions for new logical plan
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Key: PIG-1587
URL: https://issues.apache.org/jira/browse/PIG-1587
Project: Pig
Issue Type: Improvement
Components: impl
Affects Versions: 0.8.0
Reporter: Daniel Dai
Fix For: 0.9.0
We sometimes need to copy a logical operator/plan when writing an optimization
rule. Currently copy an operator/plan is awkward. We need to write some
utilities to facilitate this process. Swati contribute PIG-1510 but we feel it
still cannot address most use cases. I propose to add some more utilities into
new logical plan:
all LogicalExpressions:
{code}
copy(LogicalExpressionPlan newPlan, boolean keepUid);
{code}
* Do a shallow copy of the logical expression operator (except for fieldSchema,
uidOnlySchema, ProjectExpression.attachedRelationalOp)
* Set the plan to newPlan
* If keepUid is true, further copy uidOnlyFieldSchema
all LogicalRelationalOperators:
{code}
copy(LogicalPlan newPlan, boolean keepUid);
{code}
* Do a shallow copy of the logical relational operator (except for schema, uid
related fields)
* Set the plan to newPlan;
* If the operator have inner plan/expression plan, copy the whole inner plan
with the same keepUid flag (Especially, LOInnerLoad will copy its inner
project, with the same keepUid flag)
* If keepUid is true, further copy uid related fields (LOUnion.uidMapping,
LOCogroup.groupKeyUidOnlySchema, LOCogroup.generatedInputUids)
LogicalExpressionPlan.java
{code}
LogicalExpressionPlan copy(LogicalRelationalOperator attachedRelationalOp,
boolean keepUid);
{code}
* Copy expression operator along with connection with the same keepUid flag
* Set all ProjectExpression.attachedRelationalOp to attachedRelationalOp
parameter
{code}
List<Operator> merge(LogicalExpressionPlan plan);
{code}
* Merge plan into the current logical expression plan as an independent tree
* return the sources of this independent tree
LogicalPlan.java
{code}
LogicalPlan copy(boolean keepUid);
{code}
* Main use case to copy inner plan of ForEach
* Copy all relational operator along with connection
* Copy all expression plans inside relational operator, set plan and
attachedRelationalOp properly
{code}
List<Operator> merge(LogicalPlan plan);
{code}
* Merge plan into the current logical plan as an independent tree
* return the sources of this independent tree
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