-C New\stest\scases\sfor\swindow\sfunctions\swith\sRANGE\sBETWEEN\sand\sDESC\sNULLS\sFIRST.
-D 2019-08-30T16:46:12.848
+C Add\sfurther\scomments\sto\swindow.c.
+D 2019-08-30T17:28:55.760
F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
F src/whereInt.h 4a296fd4fa79fdcbc2b5e8c1b898901617655811223e1082b899c23ecb092217
F src/wherecode.c 535c8e228478fd971b9a5b6cb6773995b0fbf7020d5989508a5094ce5b8cd95b
F src/whereexpr.c 2757afbd5cfdbb420f9d0392e1bd5f5c0e33dee50a8c692befc7e502308e449f
-F src/window.c 701bea99097fd9f2c49e0af54446c986853e639fa297248ea62fac5e3f3b8dba
+F src/window.c ff37ca403ad3c47bb1e60b0e88c546aa5194524dc20d7f75e866187a093ae5d7
F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
F test/affinity2.test b03930d288e38b07f55023a58538ad174605695e98934bdab1facf6bd9ecc436
F test/affinity3.test 6a101af2fc945ce2912f6fe54dd646018551710d
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 39b4cad4a51bb5116d62ffb16ac36d96a9280321b049eb2d008605392f52a459
-R 5b7566c6e8c614d220a50ba45c732f15
-U drh
-Z 7f59914616f53a7b55c42685c9ae4ee5
+P f7002f86c780e279c9f8a6268f317586519c059c9de2115ff6f1cad272570c29
+R 717428315655334cbf16abae9c8648f7
+U dan
+Z e01e05b9266977bc594b107aacdc1011
typedef struct WindowCodeArg WindowCodeArg;
typedef struct WindowCsrAndReg WindowCsrAndReg;
+
+/*
+** See comments above struct WindowCodeArg.
+*/
struct WindowCsrAndReg {
- int csr;
- int reg;
+ int csr; /* Cursor number */
+ int reg; /* First in array of peer values */
};
+/*
+** A single instance of this structure is allocated on the stack by
+** sqlite3WindowCodeStep() and a pointer to it passed to the various helper
+** routines. This is to reduce the number of arguments required by each
+** helper function.
+**
+** regArg:
+** Each window function requires an accumulator register (just as an
+** ordinary aggregate function does). This variable is set to the first
+** in an array of accumulator registers - one for each window function
+** in the WindowCodeArg.pMWin list.
+**
+** eDelete:
+** The window functions implementation sometimes caches the input rows
+** that it processes in a temporary table. If it is not zero, this
+** variable indicates when rows may be removed from the temp table (in
+** order to reduce memory requirements - it would always be safe just
+** to leave them there). Possible values for eDelete are:
+**
+** WINDOW_RETURN_ROW:
+** An input row can be discarded after it is returned to the caller.
+**
+** WINDOW_AGGINVERSE:
+** An input row can be discarded after the window functions xInverse()
+** callbacks have been invoked in it.
+**
+** WINDOW_AGGSTEP:
+** An input row can be discarded after the window functions xStep()
+** callbacks have been invoked in it.
+**
+** start,current,end
+** Consider a window-frame similar to the following:
+**
+** (ORDER BY a, b GROUPS BETWEEN 2 PRECEDING AND 2 FOLLOWING)
+**
+** The windows functions implmentation caches the input rows in a temp
+** table, sorted by "a, b" (it actually populates the cache lazily, and
+** aggressively removes rows once they are no longer required, but that's
+** a mere detail). It keeps three cursors open on the temp table. One
+** (current) that points to the next row to return to the query engine
+** once its window function values have been calculated. Another (end)
+** points to the next row to call the xStep() method of each window function
+** on (so that it is 2 groups ahead of current). And a third (start) that
+** points to the next row to call the xInverse() method of each window
+** function on.
+**
+** Each cursor (start, current and end) consists of a VDBE cursor
+** (WindowCsrAndReg.csr) and an array of registers (starting at
+** WindowCodeArg.reg) that always contains a copy of the peer values
+** read from the corresponding cursor.
+**
+** Depending on the window-frame in question, all three cursors may not
+** be required. In this case both WindowCodeArg.csr and reg are set to
+** 0.
+*/
struct WindowCodeArg {
- Parse *pParse;
- Window *pMWin;
- Vdbe *pVdbe;
- int regGosub;
- int addrGosub;
- int regArg;
- int eDelete;
+ Parse *pParse; /* Parse context */
+ Window *pMWin; /* First in list of functions being processed */
+ Vdbe *pVdbe; /* VDBE object */
+ int addrGosub; /* OP_Gosub to this address to return one row */
+ int regGosub; /* Register used with OP_Gosub(addrGosub) */
+ int regArg; /* First in array of accumulator registers */
+ int eDelete; /* See above */
WindowCsrAndReg start;
WindowCsrAndReg current;
*/
static void windowCodeRangeTest(
WindowCodeArg *p,
- int op, /* OP_Ge, OP_Gt, or OP_Le */
- int csr1, /* Cursor number for cursor 1 */
- int regVal, /* Register containing non-negative number */
- int csr2, /* Cursor number for cursor 2 */
- int lbl /* Jump destination if the condition is true */
+ int op, /* OP_Ge, OP_Gt, or OP_Le */
+ int csr1, /* Cursor number for cursor 1 */
+ int regVal, /* Register containing non-negative number */
+ int csr2, /* Cursor number for cursor 2 */
+ int lbl /* Jump destination if condition is true */
){
Parse *pParse = p->pParse;
Vdbe *v = sqlite3GetVdbe(pParse);
- ExprList *pOrderBy = p->pMWin->pOrderBy; /* ORDER BY clause for this window */
- int reg1 = sqlite3GetTempReg(pParse); /* Register for csr1.peerVal+regVal */
- int reg2 = sqlite3GetTempReg(pParse); /* Regiser for csr2.peerVal */
- int regString = ++pParse->nMem; /* Register for constant value '' */
+ ExprList *pOrderBy = p->pMWin->pOrderBy; /* ORDER BY clause for window */
+ int reg1 = sqlite3GetTempReg(pParse); /* Reg. for csr1.peerVal+regVal */
+ int reg2 = sqlite3GetTempReg(pParse); /* Reg. for csr2.peerVal */
+ int regString = ++pParse->nMem; /* Reg. for constant value '' */
int arith = OP_Add; /* OP_Add or OP_Subtract */
int addrGe; /* Jump destination */
projects / thirdparty / sqlite.git / commitdiff
