Value-level operations are represented internally in an "expression tree" data structure. Expression trees may appear in the Statistics and Diagnostics Area (PXX) DUMPS=FULL or DUMPS=TRACE Reports when traces are turned on, or to provide additional information for certain SQLCODE errors (also see Dumping SQL Internal Control Structures). For example, an attempt to compare a string and a number causes the predicate to be dumped.
The expression tree dump is printed in the following format. The dump is provided primarily for CA Support to assist in debugging a problem.
LVL 1 NODE hhhhhhhh OP=hhhhhhhh NXT=hhhhhhhh$L¢ QCB=hhhhhhhh VAL=hhhhhhhh NAM=hhhhhhhh
$... . PROCTYPE = hhhh STEP=nn OPER = nnn xxxxxxxx¢
... . tblTyp (#nnnn:nnnn.nnnn): dataType $NOT NULL¢ $POSITIVE ONLY¢
$... . NAME: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx¢
$... . value¢
$... . CONTENTS=¢
LVL 2
LVL n
Line 1
This line indicates the position of the node in the tree structure and various addresses, which are all in hex. The following are the headings and descriptions.
Node level within tree displayed. (Sometimes only a sub-tree of a larger tree is displayed.)
Address of node.
Address of first operand. Zero indicates a leaf node.
Address of next node at same level or, if suffixed with L, address of result (next higher) node. Indicates the node is the last (or only) node at the top level. When only a sub-tree is being displayed, NXT may be temporarily set to zero.
Address of Query Control Block.
Address of value.
Address of name. Name is not available in all cases.
Line 2
This line does not appear for leaf nodes. In other words, it only appears if the node is the result of an operation. The following are the headings and descriptions.
Internal bit values that indicate the process class, (such as predicate, scalar function), or attribute of value (such as descending ORDER BY column).
Step in which value is computed or made available. Not applicable for all node types.
Operation performed by node. The number is a subscript into a function pointer table. It is followed by an abbreviation of the function name.
Line 3
The following are the headings and descriptions.
Indicates type of table:
Constraint
Result of a column data type conversion
Output host variable
Input host variable
Key definition
Literal
Result of a value-level operation, such as the result of an expression, function, or data type conversion
Indicates VALUE is a Query Control Block
Special register
Reference to column in table, where "nn" refers to the table's position in the FROM clause, relative to zero
Column number.
Offset in the row and the length in number of bytes.
Data type, using CREATE TABLE syntax.
Indicates value does not have a null indicator.
Indicates column reference is a numeric data type with only positive signed values. (CA Datacom Datadictionary FIELD entity-occurrence attribute TYPE-NUMERIC=P.)
Line 4 (NAME:)
Name of value, if any. NAME may not be available if dump is at execution-time.
Line 5 (value)
This line appears when the node's value is one of the following special types. The following are the headings and descriptions.
Hex dump of key definition in internal format.
Unresolved column reference.
"authID.tableName.columnName" of unresolved column reference.
Line 6 (CONTENTS=)
This line appears when the node's value is not one of the special cases shown in line 5. The following are the headings and descriptions.
NULL value.
Value dumped in hex format.
Only the first 48 bytes are displayed. Value is terminated by a period (so the number of trailing blanks can be determined).
Data types NUMERIC and DECIMAL are dumped in hex format.
The date and time displayed in ISO format.
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