65 lines
2.3 KiB
C
65 lines
2.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* windowapi.h
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* API for window functions to extract data from their window
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*
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* A window function does not receive its arguments in the normal way
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* (and therefore the concept of strictness is irrelevant). Instead it
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* receives a "WindowObject", which it can fetch with PG_WINDOW_OBJECT()
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* (note V1 calling convention must be used). Correct call context can
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* be tested with WindowObjectIsValid(). Although argument values are
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* not passed, the call is correctly set up so that PG_NARGS() can be
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* used and argument type information can be obtained with
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* get_fn_expr_argtype(), get_fn_expr_arg_stable(), etc.
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*
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* Operations on the WindowObject allow the window function to find out
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* the current row number, total number of rows in the partition, etc
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* and to evaluate its argument expression(s) at various rows in the
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* window partition. See the header comments for each WindowObject API
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* function in nodeWindowAgg.c for details.
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*
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*
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* Portions Copyright (c) 2000-2024, PostgreSQL Global Development Group
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*
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* src/include/windowapi.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef WINDOWAPI_H
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#define WINDOWAPI_H
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/* values of "seektype" */
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#define WINDOW_SEEK_CURRENT 0
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#define WINDOW_SEEK_HEAD 1
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#define WINDOW_SEEK_TAIL 2
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/* this struct is private in nodeWindowAgg.c */
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typedef struct WindowObjectData *WindowObject;
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#define PG_WINDOW_OBJECT() ((WindowObject) fcinfo->context)
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#define WindowObjectIsValid(winobj) \
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((winobj) != NULL && IsA(winobj, WindowObjectData))
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extern void *WinGetPartitionLocalMemory(WindowObject winobj, Size sz);
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extern int64 WinGetCurrentPosition(WindowObject winobj);
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extern int64 WinGetPartitionRowCount(WindowObject winobj);
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extern void WinSetMarkPosition(WindowObject winobj, int64 markpos);
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extern bool WinRowsArePeers(WindowObject winobj, int64 pos1, int64 pos2);
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extern Datum WinGetFuncArgInPartition(WindowObject winobj, int argno,
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int relpos, int seektype, bool set_mark,
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bool *isnull, bool *isout);
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extern Datum WinGetFuncArgInFrame(WindowObject winobj, int argno,
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int relpos, int seektype, bool set_mark,
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bool *isnull, bool *isout);
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extern Datum WinGetFuncArgCurrent(WindowObject winobj, int argno,
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bool *isnull);
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#endif /* WINDOWAPI_H */
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