diff options
Diffstat (limited to 'src/include/nodes/primnodes.h')
| -rw-r--r-- | src/include/nodes/primnodes.h | 35 |
1 files changed, 32 insertions, 3 deletions
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h index 5db00199cef..3ed4d74ee35 100644 --- a/src/include/nodes/primnodes.h +++ b/src/include/nodes/primnodes.h @@ -10,7 +10,7 @@ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/nodes/primnodes.h,v 1.99 2004/05/30 23:40:39 neilc Exp $ + * $PostgreSQL: pgsql/src/include/nodes/primnodes.h,v 1.100 2004/06/09 19:08:18 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -36,14 +36,15 @@ * ordinal position (counting from 1). However, in an INSERT or UPDATE * targetlist, resno represents the attribute number of the destination * column for the item; so there may be missing or out-of-order resnos. - * In an UPDATE, it is even legal to have duplicated resnos; consider + * It is even legal to have duplicated resnos; consider * UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ... * The two meanings come together in the executor, because the planner * transforms INSERT/UPDATE tlists into a normalized form with exactly * one entry for each column of the destination table. Before that's * happened, however, it is risky to assume that resno == position. * Generally get_tle_by_resno() should be used rather than list_nth() - * to fetch tlist entries by resno. + * to fetch tlist entries by resno, and only in SELECT should you assume + * that resno is a unique identifier. * * resname is required to represent the correct column name in non-resjunk * entries of top-level SELECT targetlists, since it will be used as the @@ -541,6 +542,31 @@ typedef struct FieldSelect } FieldSelect; /* ---------------- + * FieldStore + * + * FieldStore represents the operation of modifying one field in a tuple + * value, yielding a new tuple value (the input is not touched!). Like + * the assign case of ArrayRef, this is used to implement UPDATE of a + * portion of a column. + * + * A single FieldStore can actually represent updates of several different + * fields. The parser only generates FieldStores with single-element lists, + * but the planner will collapse multiple updates of the same base column + * into one FieldStore. + * ---------------- + */ + +typedef struct FieldStore +{ + Expr xpr; + Expr *arg; /* input tuple value */ + List *newvals; /* new value(s) for field(s) */ + List *fieldnums; /* integer list of field attnums */ + Oid resulttype; /* type of result (same as type of arg) */ + /* Like RowExpr, we deliberately omit a typmod here */ +} FieldStore; + +/* ---------------- * RelabelType * * RelabelType represents a "dummy" type coercion between two binary- @@ -607,6 +633,9 @@ typedef struct CaseWhen * Placeholder node for the test value to be processed by a CASE expression. * This is effectively like a Param, but can be implemented more simply * since we need only one replacement value at a time. + * + * We also use this in nested UPDATE expressions. + * See transformAssignmentIndirection(). */ typedef struct CaseTestExpr { |