Packages

object JoinReorderDP extends PredicateHelper with Logging

Reorder the joins using a dynamic programming algorithm. This implementation is based on the paper: Access Path Selection in a Relational Database Management System. https://dl.acm.org/doi/10.1145/582095.582099

First we put all items (basic joined nodes) into level 0, then we build all two-way joins at level 1 from plans at level 0 (single items), then build all 3-way joins from plans at previous levels (two-way joins and single items), then 4-way joins ... etc, until we build all n-way joins and pick the best plan among them.

When building m-way joins, we only keep the best plan (with the lowest cost) for the same set of m items. E.g., for 3-way joins, we keep only the best plan for items {A, B, C} among plans (A J B) J C, (A J C) J B and (B J C) J A. We also prune cartesian product candidates when building a new plan if there exists no join condition involving references from both left and right. This pruning strategy significantly reduces the search space. E.g., given A J B J C J D with join conditions A.k1 = B.k1 and B.k2 = C.k2 and C.k3 = D.k3, plans maintained for each level are as follows: level 0: p({A}), p({B}), p({C}), p({D}) level 1: p({A, B}), p({B, C}), p({C, D}) level 2: p({A, B, C}), p({B, C, D}) level 3: p({A, B, C, D}) where p({A, B, C, D}) is the final output plan.

For cost evaluation, since physical costs for operators are not available currently, we use cardinalities and sizes to compute costs.

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PredicateHelper, Logging, AliasHelper, AnyRef, Any
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Type Members

  1. case class JoinPlan(itemIds: Set[Int], plan: LogicalPlan, joinConds: ExpressionSet, planCost: Cost) extends Product with Serializable

    Partial join order in a specific level.

    Partial join order in a specific level.

    itemIds

    Set of item ids participating in this partial plan.

    plan

    The plan tree with the lowest cost for these items found so far.

    joinConds

    Join conditions included in the plan.

    planCost

    The cost of this plan tree is the sum of costs of all intermediate joins.

  2. type JoinPlanMap = LinkedHashMap[Set[Int], JoinPlan]

    Map[set of item ids, join plan for these items]

Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##: Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  5. def buildBalancedPredicate(expressions: Seq[Expression], op: (Expression, Expression) => Expression): Expression

    Builds a balanced output predicate in bottom up approach, by applying binary operator op pair by pair on input predicates exprs recursively.

    Builds a balanced output predicate in bottom up approach, by applying binary operator op pair by pair on input predicates exprs recursively. Example: exprs = [a, b, c, d], op = And, returns (a And b) And (c And d) exprs = [a, b, c, d, e, f], op = And, returns ((a And b) And (c And d)) And (e And f)

    Attributes
    protected
    Definition Classes
    PredicateHelper
  6. def canEvaluate(expr: Expression, plan: LogicalPlan): Boolean

    Returns true if expr can be evaluated using only the output of plan.

    Returns true if expr can be evaluated using only the output of plan. This method can be used to determine when it is acceptable to move expression evaluation within a query plan.

    For example consider a join between two relations R(a, b) and S(c, d).

    - canEvaluate(EqualTo(a,b), R) returns true - canEvaluate(EqualTo(a,c), R) returns false - canEvaluate(Literal(1), R) returns true as literals CAN be evaluated on any plan

    Attributes
    protected
    Definition Classes
    PredicateHelper
  7. def canEvaluateWithinJoin(expr: Expression): Boolean

    Returns true iff expr could be evaluated as a condition within join.

    Returns true iff expr could be evaluated as a condition within join.

    Attributes
    protected
    Definition Classes
    PredicateHelper
  8. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.CloneNotSupportedException]) @native()
  9. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  10. def equals(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef → Any
  11. def extractPredicatesWithinOutputSet(condition: Expression, outputSet: AttributeSet): Option[Expression]

    Returns a filter that its reference is a subset of outputSet and it contains the maximum constraints from condition.

    Returns a filter that its reference is a subset of outputSet and it contains the maximum constraints from condition. This is used for predicate pushdown. When there is no such filter, None is returned.

    Attributes
    protected
    Definition Classes
    PredicateHelper
  12. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.Throwable])
  13. def findExpressionAndTrackLineageDown(exp: Expression, plan: LogicalPlan): Option[(Expression, LogicalPlan)]

    Find the origin of where the input references of expression exp were scanned in the tree of plan, and if they originate from a single leaf node.

    Find the origin of where the input references of expression exp were scanned in the tree of plan, and if they originate from a single leaf node. Returns optional tuple with Expression, undoing any projections and aliasing that has been done along the way from plan to origin, and the origin LeafNode plan from which all the exp

    Definition Classes
    PredicateHelper
  14. def getAliasMap(exprs: Seq[NamedExpression]): AttributeMap[Alias]
    Attributes
    protected
    Definition Classes
    AliasHelper
  15. def getAliasMap(plan: Aggregate): AttributeMap[Alias]
    Attributes
    protected
    Definition Classes
    AliasHelper
  16. def getAliasMap(plan: Project): AttributeMap[Alias]
    Attributes
    protected
    Definition Classes
    AliasHelper
  17. final def getClass(): Class[_ <: AnyRef]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  18. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  19. def initializeLogIfNecessary(isInterpreter: Boolean, silent: Boolean): Boolean
    Attributes
    protected
    Definition Classes
    Logging
  20. def initializeLogIfNecessary(isInterpreter: Boolean): Unit
    Attributes
    protected
    Definition Classes
    Logging
  21. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  22. def isLikelySelective(e: Expression): Boolean

    Returns whether an expression is likely to be selective

    Returns whether an expression is likely to be selective

    Definition Classes
    PredicateHelper
  23. def isNullIntolerant(expr: Expression): Boolean
    Attributes
    protected
    Definition Classes
    PredicateHelper
  24. def isTraceEnabled(): Boolean
    Attributes
    protected
    Definition Classes
    Logging
  25. def log: Logger
    Attributes
    protected
    Definition Classes
    Logging
  26. def logDebug(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  27. def logDebug(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  28. def logError(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  29. def logError(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  30. def logInfo(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  31. def logInfo(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  32. def logName: String
    Attributes
    protected
    Definition Classes
    Logging
  33. def logTrace(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  34. def logTrace(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  35. def logWarning(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  36. def logWarning(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  37. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  38. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  39. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  40. def outputWithNullability(output: Seq[Attribute], nonNullAttrExprIds: Seq[ExprId]): Seq[Attribute]
    Attributes
    protected
    Definition Classes
    PredicateHelper
  41. def replaceAlias(expr: Expression, aliasMap: AttributeMap[Alias]): Expression

    Replace all attributes, that reference an alias, with the aliased expression

    Replace all attributes, that reference an alias, with the aliased expression

    Attributes
    protected
    Definition Classes
    AliasHelper
  42. def replaceAliasButKeepName(expr: NamedExpression, aliasMap: AttributeMap[Alias]): NamedExpression

    Replace all attributes, that reference an alias, with the aliased expression, but keep the name of the outermost attribute.

    Replace all attributes, that reference an alias, with the aliased expression, but keep the name of the outermost attribute.

    Attributes
    protected
    Definition Classes
    AliasHelper
  43. def search(conf: SQLConf, items: Seq[LogicalPlan], conditions: ExpressionSet, output: Seq[Attribute]): LogicalPlan
  44. def splitConjunctivePredicates(condition: Expression): Seq[Expression]
    Attributes
    protected
    Definition Classes
    PredicateHelper
  45. def splitDisjunctivePredicates(condition: Expression): Seq[Expression]
    Attributes
    protected
    Definition Classes
    PredicateHelper
  46. final def synchronized[T0](arg0: => T0): T0
    Definition Classes
    AnyRef
  47. def toString(): String
    Definition Classes
    AnyRef → Any
  48. def trimAliases(e: Expression): Expression
    Attributes
    protected
    Definition Classes
    AliasHelper
  49. def trimNonTopLevelAliases[T <: Expression](e: T): T
    Attributes
    protected
    Definition Classes
    AliasHelper
  50. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  51. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  52. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException]) @native()

Inherited from PredicateHelper

Inherited from Logging

Inherited from AliasHelper

Inherited from AnyRef

Inherited from Any

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