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Copy pathsqlite3expert.c
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2236 lines (2021 loc) · 62.3 KB
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/*
** 2017 April 09
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
*/
#include "sqlite3expert.h"
#include <assert.h>
#include <string.h>
#include <stdio.h>
#if !defined(SQLITE_AMALGAMATION)
#if defined(SQLITE_COVERAGE_TEST) || defined(SQLITE_MUTATION_TEST)
# define SQLITE_OMIT_AUXILIARY_SAFETY_CHECKS 1
#endif
#if defined(SQLITE_OMIT_AUXILIARY_SAFETY_CHECKS)
# define ALWAYS(X) (1)
# define NEVER(X) (0)
#elif !defined(NDEBUG)
# define ALWAYS(X) ((X)?1:(assert(0),0))
# define NEVER(X) ((X)?(assert(0),1):0)
#else
# define ALWAYS(X) (X)
# define NEVER(X) (X)
#endif
#endif /* !defined(SQLITE_AMALGAMATION) */
#ifndef SQLITE_OMIT_VIRTUALTABLE
typedef sqlite3_int64 i64;
typedef sqlite3_uint64 u64;
typedef struct IdxColumn IdxColumn;
typedef struct IdxConstraint IdxConstraint;
typedef struct IdxScan IdxScan;
typedef struct IdxStatement IdxStatement;
typedef struct IdxTable IdxTable;
typedef struct IdxWrite IdxWrite;
#define STRLEN (int)strlen
/*
** A temp table name that we assume no user database will actually use.
** If this assumption proves incorrect triggers on the table with the
** conflicting name will be ignored.
*/
#define UNIQUE_TABLE_NAME "t592690916721053953805701627921227776"
/*
** A single constraint. Equivalent to either "col = ?" or "col < ?" (or
** any other type of single-ended range constraint on a column).
**
** pLink:
** Used to temporarily link IdxConstraint objects into lists while
** creating candidate indexes.
*/
struct IdxConstraint {
char *zColl; /* Collation sequence */
int bRange; /* True for range, false for eq */
int iCol; /* Constrained table column */
int bFlag; /* Used by idxFindCompatible() */
int bDesc; /* True if ORDER BY <expr> DESC */
IdxConstraint *pNext; /* Next constraint in pEq or pRange list */
IdxConstraint *pLink; /* See above */
};
/*
** A single scan of a single table.
*/
struct IdxScan {
IdxTable *pTab; /* Associated table object */
int iDb; /* Database containing table zTable */
i64 covering; /* Mask of columns required for cov. index */
IdxConstraint *pOrder; /* ORDER BY columns */
IdxConstraint *pEq; /* List of == constraints */
IdxConstraint *pRange; /* List of < constraints */
IdxScan *pNextScan; /* Next IdxScan object for same analysis */
};
/*
** Information regarding a single database table. Extracted from
** "PRAGMA table_info" by function idxGetTableInfo().
*/
struct IdxColumn {
char *zName;
char *zColl;
int iPk;
};
struct IdxTable {
int nCol;
char *zName; /* Table name */
IdxColumn *aCol;
IdxTable *pNext; /* Next table in linked list of all tables */
};
/*
** An object of the following type is created for each unique table/write-op
** seen. The objects are stored in a singly-linked list beginning at
** sqlite3expert.pWrite.
*/
struct IdxWrite {
IdxTable *pTab;
int eOp; /* SQLITE_UPDATE, DELETE or INSERT */
IdxWrite *pNext;
};
/*
** Each statement being analyzed is represented by an instance of this
** structure.
*/
struct IdxStatement {
int iId; /* Statement number */
char *zSql; /* SQL statement */
char *zIdx; /* Indexes */
char *zEQP; /* Plan */
IdxStatement *pNext;
};
/*
** A hash table for storing strings. With space for a payload string
** with each entry. Methods are:
**
** idxHashInit()
** idxHashClear()
** idxHashAdd()
** idxHashSearch()
*/
#define IDX_HASH_SIZE 1023
typedef struct IdxHashEntry IdxHashEntry;
typedef struct IdxHash IdxHash;
struct IdxHashEntry {
char *zKey; /* nul-terminated key */
char *zVal; /* nul-terminated value string */
char *zVal2; /* nul-terminated value string 2 */
IdxHashEntry *pHashNext; /* Next entry in same hash bucket */
IdxHashEntry *pNext; /* Next entry in hash */
};
struct IdxHash {
IdxHashEntry *pFirst;
IdxHashEntry *aHash[IDX_HASH_SIZE];
};
/*
** sqlite3expert object.
*/
struct sqlite3expert {
int iSample; /* Percentage of tables to sample for stat1 */
sqlite3 *db; /* User database */
sqlite3 *dbm; /* In-memory db for this analysis */
sqlite3 *dbv; /* Vtab schema for this analysis */
IdxTable *pTable; /* List of all IdxTable objects */
IdxScan *pScan; /* List of scan objects */
IdxWrite *pWrite; /* List of write objects */
IdxStatement *pStatement; /* List of IdxStatement objects */
int bRun; /* True once analysis has run */
char **pzErrmsg;
int rc; /* Error code from whereinfo hook */
IdxHash hIdx; /* Hash containing all candidate indexes */
char *zCandidates; /* For EXPERT_REPORT_CANDIDATES */
};
/*
** Allocate and return nByte bytes of zeroed memory using sqlite3_malloc().
** If the allocation fails, set *pRc to SQLITE_NOMEM and return NULL.
*/
static void *idxMalloc(int *pRc, i64 nByte){
void *pRet;
assert( *pRc==SQLITE_OK );
assert( nByte>0 );
pRet = sqlite3_malloc64(nByte);
if( pRet ){
memset(pRet, 0, nByte);
}else{
*pRc = SQLITE_NOMEM;
}
return pRet;
}
/*
** Initialize an IdxHash hash table.
*/
static void idxHashInit(IdxHash *pHash){
memset(pHash, 0, sizeof(IdxHash));
}
/*
** Reset an IdxHash hash table.
*/
static void idxHashClear(IdxHash *pHash){
int i;
for(i=0; i<IDX_HASH_SIZE; i++){
IdxHashEntry *pEntry;
IdxHashEntry *pNext;
for(pEntry=pHash->aHash[i]; pEntry; pEntry=pNext){
pNext = pEntry->pHashNext;
sqlite3_free(pEntry->zVal2);
sqlite3_free(pEntry);
}
}
memset(pHash, 0, sizeof(IdxHash));
}
/*
** Return the index of the hash bucket that the string specified by the
** arguments to this function belongs.
*/
static int idxHashString(const char *z, int n){
unsigned int ret = 0;
int i;
for(i=0; i<n; i++){
ret += (ret<<3) + (unsigned char)(z[i]);
}
return (int)(ret % IDX_HASH_SIZE);
}
/*
** If zKey is already present in the hash table, return non-zero and do
** nothing. Otherwise, add an entry with key zKey and payload string zVal to
** the hash table passed as the second argument.
*/
static int idxHashAdd(
int *pRc,
IdxHash *pHash,
const char *zKey,
const char *zVal
){
int nKey = STRLEN(zKey);
int iHash = idxHashString(zKey, nKey);
int nVal = (zVal ? STRLEN(zVal) : 0);
IdxHashEntry *pEntry;
assert( iHash>=0 );
for(pEntry=pHash->aHash[iHash]; pEntry; pEntry=pEntry->pHashNext){
if( STRLEN(pEntry->zKey)==nKey && 0==memcmp(pEntry->zKey, zKey, nKey) ){
return 1;
}
}
pEntry = idxMalloc(pRc, sizeof(IdxHashEntry) + (i64)nKey+1 + (i64)nVal+1);
if( pEntry ){
pEntry->zKey = (char*)&pEntry[1];
memcpy(pEntry->zKey, zKey, nKey);
if( zVal ){
pEntry->zVal = &pEntry->zKey[nKey+1];
memcpy(pEntry->zVal, zVal, nVal);
}
pEntry->pHashNext = pHash->aHash[iHash];
pHash->aHash[iHash] = pEntry;
pEntry->pNext = pHash->pFirst;
pHash->pFirst = pEntry;
}
return 0;
}
/*
** If zKey/nKey is present in the hash table, return a pointer to the
** hash-entry object.
*/
static IdxHashEntry *idxHashFind(IdxHash *pHash, const char *zKey, int nKey){
int iHash;
IdxHashEntry *pEntry;
if( nKey<0 ) nKey = STRLEN(zKey);
iHash = idxHashString(zKey, nKey);
assert( iHash>=0 );
for(pEntry=pHash->aHash[iHash]; pEntry; pEntry=pEntry->pHashNext){
if( STRLEN(pEntry->zKey)==nKey && 0==memcmp(pEntry->zKey, zKey, nKey) ){
return pEntry;
}
}
return 0;
}
/*
** If the hash table contains an entry with a key equal to the string
** passed as the final two arguments to this function, return a pointer
** to the payload string. Otherwise, if zKey/nKey is not present in the
** hash table, return NULL.
*/
static const char *idxHashSearch(IdxHash *pHash, const char *zKey, int nKey){
IdxHashEntry *pEntry = idxHashFind(pHash, zKey, nKey);
if( pEntry ) return pEntry->zVal;
return 0;
}
/*
** Allocate and return a new IdxConstraint object. Set the IdxConstraint.zColl
** variable to point to a copy of nul-terminated string zColl.
*/
static IdxConstraint *idxNewConstraint(int *pRc, const char *zColl){
IdxConstraint *pNew;
int nColl = STRLEN(zColl);
assert( *pRc==SQLITE_OK );
pNew = (IdxConstraint*)idxMalloc(pRc, sizeof(IdxConstraint) * nColl + 1);
if( pNew ){
pNew->zColl = (char*)&pNew[1];
memcpy(pNew->zColl, zColl, nColl+1);
}
return pNew;
}
/*
** An error associated with database handle db has just occurred. Pass
** the error message to callback function xOut.
*/
static void idxDatabaseError(
sqlite3 *db, /* Database handle */
char **pzErrmsg /* Write error here */
){
*pzErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(db));
}
/*
** Prepare an SQL statement.
*/
static int idxPrepareStmt(
sqlite3 *db, /* Database handle to compile against */
sqlite3_stmt **ppStmt, /* OUT: Compiled SQL statement */
char **pzErrmsg, /* OUT: sqlite3_malloc()ed error message */
const char *zSql /* SQL statement to compile */
){
int rc = sqlite3_prepare_v2(db, zSql, -1, ppStmt, 0);
if( rc!=SQLITE_OK ){
*ppStmt = 0;
idxDatabaseError(db, pzErrmsg);
}
return rc;
}
/*
** Prepare an SQL statement using the results of a printf() formatting.
*/
static int idxPrintfPrepareStmt(
sqlite3 *db, /* Database handle to compile against */
sqlite3_stmt **ppStmt, /* OUT: Compiled SQL statement */
char **pzErrmsg, /* OUT: sqlite3_malloc()ed error message */
const char *zFmt, /* printf() format of SQL statement */
... /* Trailing printf() arguments */
){
va_list ap;
int rc;
char *zSql;
va_start(ap, zFmt);
zSql = sqlite3_vmprintf(zFmt, ap);
if( zSql==0 ){
rc = SQLITE_NOMEM;
}else{
rc = idxPrepareStmt(db, ppStmt, pzErrmsg, zSql);
sqlite3_free(zSql);
}
va_end(ap);
return rc;
}
/*************************************************************************
** Beginning of virtual table implementation.
*/
typedef struct ExpertVtab ExpertVtab;
struct ExpertVtab {
sqlite3_vtab base;
IdxTable *pTab;
sqlite3expert *pExpert;
};
typedef struct ExpertCsr ExpertCsr;
struct ExpertCsr {
sqlite3_vtab_cursor base;
sqlite3_stmt *pData;
};
static char *expertDequote(const char *zIn){
i64 n = STRLEN(zIn);
char *zRet = sqlite3_malloc64(n);
assert( zIn[0]=='\'' );
assert( zIn[n-1]=='\'' );
if( zRet ){
i64 iOut = 0;
i64 iIn = 0;
for(iIn=1; iIn<(n-1); iIn++){
if( zIn[iIn]=='\'' ){
assert( zIn[iIn+1]=='\'' );
iIn++;
}
zRet[iOut++] = zIn[iIn];
}
zRet[iOut] = '\0';
}
return zRet;
}
/*
** This function is the implementation of both the xConnect and xCreate
** methods of the r-tree virtual table.
**
** argv[0] -> module name
** argv[1] -> database name
** argv[2] -> table name
** argv[...] -> column names...
*/
static int expertConnect(
sqlite3 *db,
void *pAux,
int argc, const char *const*argv,
sqlite3_vtab **ppVtab,
char **pzErr
){
sqlite3expert *pExpert = (sqlite3expert*)pAux;
ExpertVtab *p = 0;
int rc;
if( argc!=4 ){
*pzErr = sqlite3_mprintf("internal error!");
rc = SQLITE_ERROR;
}else{
char *zCreateTable = expertDequote(argv[3]);
if( zCreateTable ){
rc = sqlite3_declare_vtab(db, zCreateTable);
if( rc==SQLITE_OK ){
p = idxMalloc(&rc, sizeof(ExpertVtab));
}
if( rc==SQLITE_OK ){
p->pExpert = pExpert;
p->pTab = pExpert->pTable;
assert( sqlite3_stricmp(p->pTab->zName, argv[2])==0 );
}
sqlite3_free(zCreateTable);
}else{
rc = SQLITE_NOMEM;
}
}
*ppVtab = (sqlite3_vtab*)p;
return rc;
}
static int expertDisconnect(sqlite3_vtab *pVtab){
ExpertVtab *p = (ExpertVtab*)pVtab;
sqlite3_free(p);
return SQLITE_OK;
}
static int expertBestIndex(sqlite3_vtab *pVtab, sqlite3_index_info *pIdxInfo){
ExpertVtab *p = (ExpertVtab*)pVtab;
int rc = SQLITE_OK;
int n = 0;
IdxScan *pScan;
const int opmask =
SQLITE_INDEX_CONSTRAINT_EQ | SQLITE_INDEX_CONSTRAINT_GT |
SQLITE_INDEX_CONSTRAINT_LT | SQLITE_INDEX_CONSTRAINT_GE |
SQLITE_INDEX_CONSTRAINT_LE;
pScan = idxMalloc(&rc, sizeof(IdxScan));
if( pScan ){
int i;
/* Link the new scan object into the list */
pScan->pTab = p->pTab;
pScan->pNextScan = p->pExpert->pScan;
p->pExpert->pScan = pScan;
/* Add the constraints to the IdxScan object */
for(i=0; i<pIdxInfo->nConstraint; i++){
struct sqlite3_index_constraint *pCons = &pIdxInfo->aConstraint[i];
if( pCons->usable
&& pCons->iColumn>=0
&& p->pTab->aCol[pCons->iColumn].iPk==0
&& (pCons->op & opmask)
){
IdxConstraint *pNew;
const char *zColl = sqlite3_vtab_collation(pIdxInfo, i);
pNew = idxNewConstraint(&rc, zColl);
if( pNew ){
pNew->iCol = pCons->iColumn;
if( pCons->op==SQLITE_INDEX_CONSTRAINT_EQ ){
pNew->pNext = pScan->pEq;
pScan->pEq = pNew;
}else{
pNew->bRange = 1;
pNew->pNext = pScan->pRange;
pScan->pRange = pNew;
}
}
n++;
pIdxInfo->aConstraintUsage[i].argvIndex = n;
}
}
/* Add the ORDER BY to the IdxScan object */
for(i=pIdxInfo->nOrderBy-1; i>=0; i--){
int iCol = pIdxInfo->aOrderBy[i].iColumn;
if( iCol>=0 ){
IdxConstraint *pNew = idxNewConstraint(&rc, p->pTab->aCol[iCol].zColl);
if( pNew ){
pNew->iCol = iCol;
pNew->bDesc = pIdxInfo->aOrderBy[i].desc;
pNew->pNext = pScan->pOrder;
pNew->pLink = pScan->pOrder;
pScan->pOrder = pNew;
n++;
}
}
}
}
pIdxInfo->estimatedCost = 1000000.0 / (n+1);
return rc;
}
static int expertUpdate(
sqlite3_vtab *pVtab,
int nData,
sqlite3_value **azData,
sqlite_int64 *pRowid
){
(void)pVtab;
(void)nData;
(void)azData;
(void)pRowid;
return SQLITE_OK;
}
/*
** Virtual table module xOpen method.
*/
static int expertOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
int rc = SQLITE_OK;
ExpertCsr *pCsr;
(void)pVTab;
pCsr = idxMalloc(&rc, sizeof(ExpertCsr));
*ppCursor = (sqlite3_vtab_cursor*)pCsr;
return rc;
}
/*
** Virtual table module xClose method.
*/
static int expertClose(sqlite3_vtab_cursor *cur){
ExpertCsr *pCsr = (ExpertCsr*)cur;
sqlite3_finalize(pCsr->pData);
sqlite3_free(pCsr);
return SQLITE_OK;
}
/*
** Virtual table module xEof method.
**
** Return non-zero if the cursor does not currently point to a valid
** record (i.e if the scan has finished), or zero otherwise.
*/
static int expertEof(sqlite3_vtab_cursor *cur){
ExpertCsr *pCsr = (ExpertCsr*)cur;
return pCsr->pData==0;
}
/*
** Virtual table module xNext method.
*/
static int expertNext(sqlite3_vtab_cursor *cur){
ExpertCsr *pCsr = (ExpertCsr*)cur;
int rc = SQLITE_OK;
assert( pCsr->pData );
rc = sqlite3_step(pCsr->pData);
if( rc!=SQLITE_ROW ){
rc = sqlite3_finalize(pCsr->pData);
pCsr->pData = 0;
}else{
rc = SQLITE_OK;
}
return rc;
}
/*
** Virtual table module xRowid method.
*/
static int expertRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
(void)cur;
*pRowid = 0;
return SQLITE_OK;
}
/*
** Virtual table module xColumn method.
*/
static int expertColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){
ExpertCsr *pCsr = (ExpertCsr*)cur;
sqlite3_value *pVal;
pVal = sqlite3_column_value(pCsr->pData, i);
if( pVal ){
sqlite3_result_value(ctx, pVal);
}
return SQLITE_OK;
}
/*
** Virtual table module xFilter method.
*/
static int expertFilter(
sqlite3_vtab_cursor *cur,
int idxNum, const char *idxStr,
int argc, sqlite3_value **argv
){
ExpertCsr *pCsr = (ExpertCsr*)cur;
ExpertVtab *pVtab = (ExpertVtab*)(cur->pVtab);
sqlite3expert *pExpert = pVtab->pExpert;
int rc;
(void)idxNum;
(void)idxStr;
(void)argc;
(void)argv;
rc = sqlite3_finalize(pCsr->pData);
pCsr->pData = 0;
if( rc==SQLITE_OK ){
rc = idxPrintfPrepareStmt(pExpert->db, &pCsr->pData, &pVtab->base.zErrMsg,
"SELECT * FROM main.%Q WHERE sqlite_expert_sample()", pVtab->pTab->zName
);
}
if( rc==SQLITE_OK ){
rc = expertNext(cur);
}
return rc;
}
static int idxRegisterVtab(sqlite3expert *p){
static sqlite3_module expertModule = {
2, /* iVersion */
expertConnect, /* xCreate - create a table */
expertConnect, /* xConnect - connect to an existing table */
expertBestIndex, /* xBestIndex - Determine search strategy */
expertDisconnect, /* xDisconnect - Disconnect from a table */
expertDisconnect, /* xDestroy - Drop a table */
expertOpen, /* xOpen - open a cursor */
expertClose, /* xClose - close a cursor */
expertFilter, /* xFilter - configure scan constraints */
expertNext, /* xNext - advance a cursor */
expertEof, /* xEof */
expertColumn, /* xColumn - read data */
expertRowid, /* xRowid - read data */
expertUpdate, /* xUpdate - write data */
0, /* xBegin - begin transaction */
0, /* xSync - sync transaction */
0, /* xCommit - commit transaction */
0, /* xRollback - rollback transaction */
0, /* xFindFunction - function overloading */
0, /* xRename - rename the table */
0, /* xSavepoint */
0, /* xRelease */
0, /* xRollbackTo */
0, /* xShadowName */
0, /* xIntegrity */
};
return sqlite3_create_module(p->dbv, "expert", &expertModule, (void*)p);
}
/*
** End of virtual table implementation.
*************************************************************************/
/*
** Finalize SQL statement pStmt. If (*pRc) is SQLITE_OK when this function
** is called, set it to the return value of sqlite3_finalize() before
** returning. Otherwise, discard the sqlite3_finalize() return value.
*/
static void idxFinalize(int *pRc, sqlite3_stmt *pStmt){
int rc = sqlite3_finalize(pStmt);
if( *pRc==SQLITE_OK ) *pRc = rc;
}
/*
** Attempt to allocate an IdxTable structure corresponding to table zTab
** in the main database of connection db. If successful, set (*ppOut) to
** point to the new object and return SQLITE_OK. Otherwise, return an
** SQLite error code and set (*ppOut) to NULL. In this case *pzErrmsg may be
** set to point to an error string.
**
** It is the responsibility of the caller to eventually free either the
** IdxTable object or error message using sqlite3_free().
*/
static int idxGetTableInfo(
sqlite3 *db, /* Database connection to read details from */
const char *zTab, /* Table name */
IdxTable **ppOut, /* OUT: New object (if successful) */
char **pzErrmsg /* OUT: Error message (if not) */
){
sqlite3_stmt *p1 = 0;
int nCol = 0;
int nTab;
i64 nByte;
IdxTable *pNew = 0;
int rc, rc2;
char *pCsr = 0;
int nPk = 0;
*ppOut = 0;
if( zTab==0 ) return SQLITE_ERROR;
nTab = STRLEN(zTab);
nByte = sizeof(IdxTable) + nTab + 1;
rc = idxPrintfPrepareStmt(db, &p1, pzErrmsg, "PRAGMA table_xinfo=%Q", zTab);
while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(p1) ){
const char *zCol = (const char*)sqlite3_column_text(p1, 1);
const char *zColSeq = 0;
if( zCol==0 ){
rc = SQLITE_ERROR;
break;
}
nByte += 1 + STRLEN(zCol);
rc = sqlite3_table_column_metadata(
db, "main", zTab, zCol, 0, &zColSeq, 0, 0, 0
);
if( zColSeq==0 ) zColSeq = "binary";
nByte += 1 + STRLEN(zColSeq);
nCol++;
nPk += (sqlite3_column_int(p1, 5)>0);
}
rc2 = sqlite3_reset(p1);
if( rc==SQLITE_OK ) rc = rc2;
nByte += sizeof(IdxColumn) * nCol;
if( rc==SQLITE_OK ){
pNew = idxMalloc(&rc, nByte);
}
if( rc==SQLITE_OK ){
pNew->aCol = (IdxColumn*)&pNew[1];
pNew->nCol = nCol;
pCsr = (char*)&pNew->aCol[nCol];
}
nCol = 0;
while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(p1) ){
const char *zCol = (const char*)sqlite3_column_text(p1, 1);
const char *zColSeq = 0;
int nCopy;
if( zCol==0 ) continue;
nCopy = STRLEN(zCol) + 1;
pNew->aCol[nCol].zName = pCsr;
pNew->aCol[nCol].iPk = (sqlite3_column_int(p1, 5)==1 && nPk==1);
memcpy(pCsr, zCol, nCopy);
pCsr += nCopy;
rc = sqlite3_table_column_metadata(
db, "main", zTab, zCol, 0, &zColSeq, 0, 0, 0
);
if( rc==SQLITE_OK ){
if( zColSeq==0 ) zColSeq = "binary";
nCopy = STRLEN(zColSeq) + 1;
pNew->aCol[nCol].zColl = pCsr;
memcpy(pCsr, zColSeq, nCopy);
pCsr += nCopy;
}
nCol++;
}
idxFinalize(&rc, p1);
if( rc!=SQLITE_OK ){
sqlite3_free(pNew);
pNew = 0;
}else if( ALWAYS(pNew!=0) ){
pNew->zName = pCsr;
if( ALWAYS(pNew->zName!=0) ) memcpy(pNew->zName, zTab, nTab+1);
}
*ppOut = pNew;
return rc;
}
/*
** This function is a no-op if *pRc is set to anything other than
** SQLITE_OK when it is called.
**
** If *pRc is initially set to SQLITE_OK, then the text specified by
** the printf() style arguments is appended to zIn and the result returned
** in a buffer allocated by sqlite3_malloc(). sqlite3_free() is called on
** zIn before returning.
*/
static char *idxAppendText(int *pRc, char *zIn, const char *zFmt, ...){
va_list ap;
char *zAppend = 0;
char *zRet = 0;
i64 nIn = zIn ? STRLEN(zIn) : 0;
i64 nAppend = 0;
va_start(ap, zFmt);
if( *pRc==SQLITE_OK ){
zAppend = sqlite3_vmprintf(zFmt, ap);
if( zAppend ){
nAppend = STRLEN(zAppend);
zRet = (char*)sqlite3_malloc64(nIn + nAppend + 1);
}
if( zAppend && zRet ){
if( nIn ) memcpy(zRet, zIn, nIn);
memcpy(&zRet[nIn], zAppend, nAppend+1);
}else{
sqlite3_free(zRet);
zRet = 0;
*pRc = SQLITE_NOMEM;
}
sqlite3_free(zAppend);
sqlite3_free(zIn);
}
va_end(ap);
return zRet;
}
/*
** Return true if zId must be quoted in order to use it as an SQL
** identifier, or false otherwise.
*/
static int idxIdentifierRequiresQuotes(const char *zId){
int i;
int nId = STRLEN(zId);
if( sqlite3_keyword_check(zId, nId) ) return 1;
for(i=0; zId[i]; i++){
if( !(zId[i]=='_')
&& !(zId[i]>='0' && zId[i]<='9')
&& !(zId[i]>='a' && zId[i]<='z')
&& !(zId[i]>='A' && zId[i]<='Z')
){
return 1;
}
}
return 0;
}
/*
** This function appends an index column definition suitable for constraint
** pCons to the string passed as zIn and returns the result.
*/
static char *idxAppendColDefn(
int *pRc, /* IN/OUT: Error code */
char *zIn, /* Column defn accumulated so far */
IdxTable *pTab, /* Table index will be created on */
IdxConstraint *pCons
){
char *zRet = zIn;
IdxColumn *p = &pTab->aCol[pCons->iCol];
if( zRet ) zRet = idxAppendText(pRc, zRet, ", ");
if( idxIdentifierRequiresQuotes(p->zName) ){
zRet = idxAppendText(pRc, zRet, "%Q", p->zName);
}else{
zRet = idxAppendText(pRc, zRet, "%s", p->zName);
}
if( sqlite3_stricmp(p->zColl, pCons->zColl) ){
if( idxIdentifierRequiresQuotes(pCons->zColl) ){
zRet = idxAppendText(pRc, zRet, " COLLATE %Q", pCons->zColl);
}else{
zRet = idxAppendText(pRc, zRet, " COLLATE %s", pCons->zColl);
}
}
if( pCons->bDesc ){
zRet = idxAppendText(pRc, zRet, " DESC");
}
return zRet;
}
/*
** Search database dbm for an index compatible with the one idxCreateFromCons()
** would create from arguments pScan, pEq and pTail. If no error occurs and
** such an index is found, return non-zero. Or, if no such index is found,
** return zero.
**
** If an error occurs, set *pRc to an SQLite error code and return zero.
*/
static int idxFindCompatible(
int *pRc, /* OUT: Error code */
sqlite3* dbm, /* Database to search */
IdxScan *pScan, /* Scan for table to search for index on */
IdxConstraint *pEq, /* List of == constraints */
IdxConstraint *pTail /* List of range constraints */
){
const char *zTbl = pScan->pTab->zName;
sqlite3_stmt *pIdxList = 0;
IdxConstraint *pIter;
int nEq = 0; /* Number of elements in pEq */
int rc;
/* Count the elements in list pEq */
for(pIter=pEq; pIter; pIter=pIter->pLink) nEq++;
rc = idxPrintfPrepareStmt(dbm, &pIdxList, 0, "PRAGMA index_list=%Q", zTbl);
while( rc==SQLITE_OK && sqlite3_step(pIdxList)==SQLITE_ROW ){
int bMatch = 1;
IdxConstraint *pT = pTail;
sqlite3_stmt *pInfo = 0;
const char *zIdx = (const char*)sqlite3_column_text(pIdxList, 1);
if( zIdx==0 ) continue;
/* Zero the IdxConstraint.bFlag values in the pEq list */
for(pIter=pEq; pIter; pIter=pIter->pLink) pIter->bFlag = 0;
rc = idxPrintfPrepareStmt(dbm, &pInfo, 0, "PRAGMA index_xInfo=%Q", zIdx);
while( rc==SQLITE_OK && sqlite3_step(pInfo)==SQLITE_ROW ){
int iIdx = sqlite3_column_int(pInfo, 0);
int iCol = sqlite3_column_int(pInfo, 1);
const char *zColl = (const char*)sqlite3_column_text(pInfo, 4);
if( iIdx<nEq ){
for(pIter=pEq; pIter; pIter=pIter->pLink){
if( pIter->bFlag ) continue;
if( pIter->iCol!=iCol ) continue;
if( sqlite3_stricmp(pIter->zColl, zColl) ) continue;
pIter->bFlag = 1;
break;
}
if( pIter==0 ){
bMatch = 0;
break;
}
}else{
if( pT ){
if( pT->iCol!=iCol || sqlite3_stricmp(pT->zColl, zColl) ){
bMatch = 0;
break;
}
pT = pT->pLink;
}
}
}
idxFinalize(&rc, pInfo);
if( rc==SQLITE_OK && bMatch ){
sqlite3_finalize(pIdxList);
return 1;
}
}
idxFinalize(&rc, pIdxList);
*pRc = rc;
return 0;
}
/* Callback for sqlite3_exec() with query with leading count(*) column.
* The first argument is expected to be an int*, referent to be incremented
* if that leading column is not exactly '0'.
*/
static int countNonzeros(void* pCount, int nc,
char* azResults[], char* azColumns[]){
(void)azColumns; /* Suppress unused parameter warning */
if( nc>0 && (azResults[0][0]!='0' || azResults[0][1]!=0) ){
*((int *)pCount) += 1;
}
return 0;
}
static int idxCreateFromCons(
sqlite3expert *p,
IdxScan *pScan,
IdxConstraint *pEq,
IdxConstraint *pTail
){
sqlite3 *dbm = p->dbm;
int rc = SQLITE_OK;
if( (pEq || pTail) && 0==idxFindCompatible(&rc, dbm, pScan, pEq, pTail) ){
IdxTable *pTab = pScan->pTab;
char *zCols = 0;
char *zIdx = 0;
IdxConstraint *pCons;
unsigned int h = 0;
const char *zFmt;
for(pCons=pEq; pCons; pCons=pCons->pLink){
zCols = idxAppendColDefn(&rc, zCols, pTab, pCons);
}
for(pCons=pTail; pCons; pCons=pCons->pLink){
zCols = idxAppendColDefn(&rc, zCols, pTab, pCons);
}
if( rc==SQLITE_OK ){
/* Hash the list of columns to come up with a name for the index */
const char *zTable = pScan->pTab->zName;
int quoteTable = idxIdentifierRequiresQuotes(zTable);
char *zName = 0; /* Index name */
int collisions = 0;
do{
int i;
char *zFind;
for(i=0; zCols[i]; i++){
h += ((h<<3) + zCols[i]);
}
sqlite3_free(zName);
zName = sqlite3_mprintf("%s_idx_%08x", zTable, h);
if( zName==0 ) break;