627 lines
16 KiB
C
627 lines
16 KiB
C
/*
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** 2017 July 15
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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*************************************************************************
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**
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*/
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#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_UNIONVTAB)
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#include "sqlite3ext.h"
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SQLITE_EXTENSION_INIT1
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#include <assert.h>
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#include <string.h>
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#ifndef SQLITE_OMIT_VIRTUALTABLE
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typedef struct UnionCsr UnionCsr;
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typedef struct UnionTab UnionTab;
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typedef struct UnionSrc UnionSrc;
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/*
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** Each source table (row returned by the initialization query) is
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** represented by an instance of the following structure stored in the
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** UnionTab.aSrc[] array.
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*/
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struct UnionSrc {
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char *zDb; /* Database containing source table */
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char *zTab; /* Source table name */
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sqlite3_int64 iMin; /* Minimum rowid */
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sqlite3_int64 iMax; /* Maximum rowid */
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};
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/*
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** Virtual table cursor type for union vtab.
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*/
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struct UnionCsr {
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sqlite3_vtab_cursor base; /* Base class - must be first */
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sqlite3_stmt *pStmt; /* SQL statement to run */
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};
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/*
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** Virtual table type for union vtab.
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*/
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struct UnionTab {
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sqlite3_vtab base; /* Base class - must be first */
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sqlite3 *db; /* Database handle */
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int nSrc; /* Number of elements in the aSrc[] array */
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UnionSrc *aSrc; /* Array of source tables, sorted by rowid */
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};
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/*
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** If *pRc is other than SQLITE_OK when this function is called, it
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** always returns NULL. Otherwise, it attempts to allocate and return
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** a pointer to nByte bytes of zeroed memory. If the memory allocation
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** is attempted but fails, NULL is returned and *pRc is set to
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** SQLITE_NOMEM.
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*/
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static void *unionMalloc(int *pRc, int nByte){
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void *pRet;
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assert( nByte>0 );
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if( *pRc==SQLITE_OK ){
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pRet = sqlite3_malloc(nByte);
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if( pRet ){
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memset(pRet, 0, nByte);
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}else{
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*pRc = SQLITE_NOMEM;
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}
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}else{
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pRet = 0;
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}
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return pRet;
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}
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/*
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** If *pRc is other than SQLITE_OK when this function is called, it
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** always returns NULL. Otherwise, it attempts to allocate and return
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** a copy of the nul-terminated string passed as the second argument.
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** If the allocation is attempted but fails, NULL is returned and *pRc is
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** set to SQLITE_NOMEM.
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*/
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static char *unionStrdup(int *pRc, const char *zIn){
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char *zRet = 0;
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if( zIn ){
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int nByte = strlen(zIn) + 1;
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zRet = unionMalloc(pRc, nByte);
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if( zRet ){
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memcpy(zRet, zIn, nByte);
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}
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}
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return zRet;
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}
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/*
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** If the first character of the string passed as the only argument to this
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** function is one of the 4 that may be used as an open quote character
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** in SQL, this function assumes that the input is a well-formed quoted SQL
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** string. In this case the string is dequoted in place.
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**
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** If the first character of the input is not an open quote, then this
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** function is a no-op.
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*/
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static void unionDequote(char *z){
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char q = z[0];
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/* Set stack variable q to the close-quote character */
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if( q=='[' || q=='\'' || q=='"' || q=='`' ){
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int iIn = 1;
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int iOut = 0;
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if( q=='[' ) q = ']';
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while( z[iIn] ){
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if( z[iIn]==q ){
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if( z[iIn+1]!=q ){
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/* Character iIn was the close quote. */
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iIn++;
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break;
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}else{
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/* Character iIn and iIn+1 form an escaped quote character. Skip
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** the input cursor past both and copy a single quote character
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** to the output buffer. */
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iIn += 2;
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z[iOut++] = q;
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}
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}else{
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z[iOut++] = z[iIn++];
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}
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}
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z[iOut] = '\0';
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}
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}
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static sqlite3_stmt *unionPrepare(
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int *pRc,
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sqlite3 *db,
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const char *zSql,
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char **pzErr
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){
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sqlite3_stmt *pRet = 0;
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if( *pRc==SQLITE_OK ){
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int rc = sqlite3_prepare_v2(db, zSql, -1, &pRet, 0);
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if( rc!=SQLITE_OK ){
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*pzErr = sqlite3_mprintf("sql error: %s", sqlite3_errmsg(db));
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*pRc = rc;
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}
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}
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return pRet;
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}
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static void unionReset(int *pRc, sqlite3_stmt *pStmt, char **pzErr){
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int rc = sqlite3_reset(pStmt);
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if( *pRc==SQLITE_OK ){
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*pRc = rc;
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if( rc && pzErr ){
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*pzErr = sqlite3_mprintf("%s", sqlite3_errmsg(sqlite3_db_handle(pStmt)));
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}
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}
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}
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static void unionFinalize(int *pRc, sqlite3_stmt *pStmt){
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int rc = sqlite3_finalize(pStmt);
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if( *pRc==SQLITE_OK ) *pRc = rc;
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}
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/*
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** xDisconnect method.
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*/
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static int unionDisconnect(sqlite3_vtab *pVtab){
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if( pVtab ){
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UnionTab *pTab = (UnionTab*)pVtab;
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int i;
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for(i=0; i<pTab->nSrc; i++){
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sqlite3_free(pTab->aSrc[i].zDb);
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sqlite3_free(pTab->aSrc[i].zTab);
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}
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sqlite3_free(pTab->aSrc);
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sqlite3_free(pTab);
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}
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return SQLITE_OK;
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}
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static char *unionSourceToStr(
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int *pRc,
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UnionSrc *pSrc,
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sqlite3_stmt *pStmt,
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char **pzErr
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){
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char *zRet = 0;
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if( *pRc==SQLITE_OK ){
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sqlite3_bind_text(pStmt, 1, pSrc->zTab, -1, SQLITE_STATIC);
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sqlite3_bind_text(pStmt, 2, pSrc->zDb, -1, SQLITE_STATIC);
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if( SQLITE_ROW==sqlite3_step(pStmt) ){
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zRet = unionStrdup(pRc, (const char*)sqlite3_column_text(pStmt, 0));
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}
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unionReset(pRc, pStmt, pzErr);
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if( *pRc==SQLITE_OK && zRet==0 ){
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*pRc = SQLITE_ERROR;
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*pzErr = sqlite3_mprintf("no such table: %s%s%s",
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(pSrc->zDb ? pSrc->zDb : ""),
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(pSrc->zDb ? "." : ""),
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pSrc->zTab
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);
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}
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}
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return zRet;
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}
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static int unionSourceCheck(UnionTab *pTab, char **pzErr){
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const char *zSql =
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"SELECT group_concat(quote(name) || '.' || quote(type)) "
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"FROM pragma_table_info(?, ?)";
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int rc = SQLITE_OK;
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if( pTab->nSrc==0 ){
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*pzErr = sqlite3_mprintf("no source tables configured");
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rc = SQLITE_ERROR;
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}else{
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sqlite3_stmt *pStmt = 0;
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char *z0 = 0;
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int i;
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pStmt = unionPrepare(&rc, pTab->db, zSql, pzErr);
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if( rc==SQLITE_OK ){
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z0 = unionSourceToStr(&rc, &pTab->aSrc[0], pStmt, pzErr);
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}
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for(i=1; i<pTab->nSrc; i++){
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char *z = unionSourceToStr(&rc, &pTab->aSrc[i], pStmt, pzErr);
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if( rc==SQLITE_OK && sqlite3_stricmp(z, z0) ){
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*pzErr = sqlite3_mprintf("source table schema mismatch");
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rc = SQLITE_ERROR;
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}
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sqlite3_free(z);
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}
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unionFinalize(&rc, pStmt);
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sqlite3_free(z0);
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}
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return rc;
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}
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/*
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** xConnect/xCreate method.
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**
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** The argv[] array contains the following:
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**
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** argv[0] -> module name ("unionvtab")
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** argv[1] -> database name
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** argv[2] -> table name
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** argv[3] -> SQL statement
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*/
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static int unionConnect(
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sqlite3 *db,
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void *pAux,
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int argc, const char *const*argv,
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sqlite3_vtab **ppVtab,
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char **pzErr
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){
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UnionTab *pTab = 0;
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int rc = SQLITE_OK;
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if( sqlite3_stricmp("temp", argv[1]) ){
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/* unionvtab tables may only be created in the temp schema */
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*pzErr = sqlite3_mprintf("unionvtab tables must be created in TEMP schema");
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rc = SQLITE_ERROR;
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}else if( argc!=4 ){
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*pzErr = sqlite3_mprintf("wrong number of arguments for unionvtab");
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rc = SQLITE_ERROR;
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}else{
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int nAlloc = 0; /* Allocated size of pTab->aSrc[] */
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sqlite3_stmt *pStmt = 0; /* Argument statement */
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char *zSql1 = unionStrdup(&rc, argv[3]);
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char *zSql2 = 0;
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if( zSql1 ){
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unionDequote(zSql1);
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zSql2 = sqlite3_mprintf("SELECT * FROM (%s) ORDER BY 3", zSql1);
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sqlite3_free(zSql1);
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zSql1 = 0;
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}
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if( zSql2==0 ){
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rc = SQLITE_NOMEM;
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}
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pTab = unionMalloc(&rc, sizeof(UnionTab));
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pStmt = unionPrepare(&rc, db, zSql2, pzErr);
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while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
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const char *zDb = (const char*)sqlite3_column_text(pStmt, 0);
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const char *zTab = (const char*)sqlite3_column_text(pStmt, 1);
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sqlite3_int64 iMin = sqlite3_column_int64(pStmt, 2);
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sqlite3_int64 iMax = sqlite3_column_int64(pStmt, 3);
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UnionSrc *pSrc;
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if( nAlloc<=pTab->nSrc ){
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int nNew = nAlloc ? nAlloc*2 : 8;
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UnionSrc *aNew = (UnionSrc*)sqlite3_realloc(
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pTab->aSrc, nNew*sizeof(UnionSrc)
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);
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if( aNew==0 ){
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rc = SQLITE_NOMEM;
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break;
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}else{
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memset(&aNew[pTab->nSrc], 0, (nNew-pTab->nSrc)*sizeof(UnionSrc));
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pTab->aSrc = aNew;
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nAlloc = nNew;
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}
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}
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if( iMax<iMin || (pTab->nSrc>0 && iMin<=pTab->aSrc[pTab->nSrc-1].iMax) ){
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*pzErr = sqlite3_mprintf("rowid range mismatch error");
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rc = SQLITE_ERROR;
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}
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pSrc = &pTab->aSrc[pTab->nSrc++];
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pSrc->zDb = unionStrdup(&rc, zDb);
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pSrc->zTab = unionStrdup(&rc, zTab);
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pSrc->iMin = iMin;
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pSrc->iMax = iMax;
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}
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unionFinalize(&rc, pStmt);
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pStmt = 0;
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sqlite3_free(zSql1);
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sqlite3_free(zSql2);
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zSql1 = 0;
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zSql2 = 0;
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/* Verify that all source tables exist and have compatible schemas. */
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if( rc==SQLITE_OK ){
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pTab->db = db;
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rc = unionSourceCheck(pTab, pzErr);
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}
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/* Compose a CREATE TABLE statement and pass it to declare_vtab() */
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if( rc==SQLITE_OK ){
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zSql1 = sqlite3_mprintf("SELECT "
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"'CREATE TABLE xyz('"
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" || group_concat(quote(name) || ' ' || type, ', ')"
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" || ')'"
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"FROM pragma_table_info(%Q, ?)",
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pTab->aSrc[0].zTab
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);
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if( zSql1==0 ) rc = SQLITE_NOMEM;
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}
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pStmt = unionPrepare(&rc, db, zSql1, pzErr);
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if( rc==SQLITE_OK ){
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sqlite3_bind_text(pStmt, 1, pTab->aSrc[0].zDb, -1, SQLITE_STATIC);
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if( SQLITE_ROW==sqlite3_step(pStmt) ){
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const char *zDecl = (const char*)sqlite3_column_text(pStmt, 0);
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rc = sqlite3_declare_vtab(db, zDecl);
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}
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}
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unionFinalize(&rc, pStmt);
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sqlite3_free(zSql1);
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}
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if( rc!=SQLITE_OK ){
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unionDisconnect((sqlite3_vtab*)pTab);
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pTab = 0;
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}
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*ppVtab = (sqlite3_vtab*)pTab;
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return rc;
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}
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/*
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** xOpen
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*/
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static int unionOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
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UnionCsr *pCsr;
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int rc = SQLITE_OK;
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pCsr = (UnionCsr*)unionMalloc(&rc, sizeof(UnionCsr));
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*ppCursor = &pCsr->base;
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return rc;
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}
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/*
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** xClose
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*/
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static int unionClose(sqlite3_vtab_cursor *cur){
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UnionCsr *pCsr = (UnionCsr*)cur;
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sqlite3_finalize(pCsr->pStmt);
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sqlite3_free(pCsr);
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return SQLITE_OK;
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}
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/*
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** xNext
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*/
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static int unionNext(sqlite3_vtab_cursor *cur){
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UnionCsr *pCsr = (UnionCsr*)cur;
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int rc;
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assert( pCsr->pStmt );
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if( sqlite3_step(pCsr->pStmt)!=SQLITE_ROW ){
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rc = sqlite3_finalize(pCsr->pStmt);
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pCsr->pStmt = 0;
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}else{
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rc = SQLITE_OK;
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}
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return rc;
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}
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/*
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** xColumn
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*/
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static int unionColumn(
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sqlite3_vtab_cursor *cur,
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sqlite3_context *ctx,
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int i
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){
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UnionCsr *pCsr = (UnionCsr*)cur;
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sqlite3_result_value(ctx, sqlite3_column_value(pCsr->pStmt, i+1));
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return SQLITE_OK;
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}
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/*
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** xRowid
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*/
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static int unionRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
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UnionCsr *pCsr = (UnionCsr*)cur;
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*pRowid = sqlite3_column_int64(pCsr->pStmt, 0);
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return SQLITE_OK;
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}
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/*
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** xEof
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*/
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static int unionEof(sqlite3_vtab_cursor *cur){
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UnionCsr *pCsr = (UnionCsr*)cur;
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return pCsr->pStmt==0;
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}
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/*
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** xFilter
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*/
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static int unionFilter(
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sqlite3_vtab_cursor *pVtabCursor,
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int idxNum, const char *idxStr,
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int argc, sqlite3_value **argv
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){
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UnionTab *pTab = (UnionTab*)(pVtabCursor->pVtab);
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UnionCsr *pCsr = (UnionCsr*)pVtabCursor;
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int rc = SQLITE_OK;
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int i;
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char *zSql = 0;
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int bMinValid = 0;
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int bMaxValid = 0;
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sqlite3_int64 iMin;
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sqlite3_int64 iMax;
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if( idxNum==SQLITE_INDEX_CONSTRAINT_EQ ){
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assert( argc==1 );
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iMin = iMax = sqlite3_value_int64(argv[0]);
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bMinValid = bMaxValid = 1;
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}else{
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if( idxNum & SQLITE_INDEX_CONSTRAINT_LE ){
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assert( argc>=1 );
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iMax = sqlite3_value_int64(argv[0]);
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bMaxValid = 1;
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}
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if( idxNum & SQLITE_INDEX_CONSTRAINT_GE ){
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assert( argc>=1 );
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iMin = sqlite3_value_int64(argv[argc-1]);
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bMinValid = 1;
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}
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}
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sqlite3_finalize(pCsr->pStmt);
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pCsr->pStmt = 0;
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for(i=0; i<pTab->nSrc; i++){
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UnionSrc *pSrc = &pTab->aSrc[i];
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if( (bMinValid && iMin>pSrc->iMax) || (bMaxValid && iMax<pSrc->iMin) ){
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continue;
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}
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zSql = sqlite3_mprintf("%z%sSELECT rowid, * FROM %s%q%s%Q"
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, zSql
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, (zSql ? " UNION ALL " : "")
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, (pSrc->zDb ? "'" : "")
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, (pSrc->zDb ? pSrc->zDb : "")
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, (pSrc->zDb ? "'." : "")
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, pSrc->zTab
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);
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if( zSql==0 ){
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rc = SQLITE_NOMEM;
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break;
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}
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if( zSql ){
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if( bMinValid && bMaxValid && iMin==iMax ){
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zSql = sqlite3_mprintf("%z WHERE rowid=%lld", zSql, iMin);
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}else{
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const char *zWhere = "WHERE";
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if( bMinValid && iMin>pSrc->iMin ){
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zSql = sqlite3_mprintf("%z WHERE rowid>=%lld", zSql, iMin);
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zWhere = "AND";
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}
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if( bMaxValid && iMax<pSrc->iMax ){
|
|
zSql = sqlite3_mprintf("%z %s rowid<=%lld", zSql, zWhere, iMax);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if( rc==SQLITE_OK ){
|
|
pCsr->pStmt = unionPrepare(&rc, pTab->db, zSql, &pTab->base.zErrMsg);
|
|
}
|
|
sqlite3_free(zSql);
|
|
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
return unionNext(pVtabCursor);
|
|
}
|
|
|
|
/*
|
|
** xBestIndex.
|
|
*/
|
|
static int unionBestIndex(
|
|
sqlite3_vtab *tab,
|
|
sqlite3_index_info *pIdxInfo
|
|
){
|
|
int iEq = -1;
|
|
int iLt = -1;
|
|
int iGt = -1;
|
|
int i;
|
|
|
|
for(i=0; i<pIdxInfo->nConstraint; i++){
|
|
struct sqlite3_index_constraint *p = &pIdxInfo->aConstraint[i];
|
|
if( p->usable && p->iColumn<0 ){
|
|
switch( p->op ){
|
|
case SQLITE_INDEX_CONSTRAINT_EQ:
|
|
if( iEq<0 ) iEq = i;
|
|
break;
|
|
case SQLITE_INDEX_CONSTRAINT_LE:
|
|
case SQLITE_INDEX_CONSTRAINT_LT:
|
|
if( iLt<0 ) iLt = i;
|
|
break;
|
|
case SQLITE_INDEX_CONSTRAINT_GE:
|
|
case SQLITE_INDEX_CONSTRAINT_GT:
|
|
if( iGt<0 ) iGt = i;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if( iEq>=0 ){
|
|
pIdxInfo->estimatedRows = 1;
|
|
pIdxInfo->idxFlags = SQLITE_INDEX_SCAN_UNIQUE;
|
|
pIdxInfo->estimatedCost = 3.0;
|
|
pIdxInfo->idxNum = SQLITE_INDEX_CONSTRAINT_EQ;
|
|
pIdxInfo->aConstraintUsage[iEq].argvIndex = 1;
|
|
}else{
|
|
int iCons = 1;
|
|
int idxNum = 0;
|
|
sqlite3_int64 nRow = 1000000;
|
|
if( iLt>=0 ){
|
|
nRow = nRow / 2;
|
|
pIdxInfo->aConstraintUsage[iLt].argvIndex = iCons++;
|
|
idxNum |= SQLITE_INDEX_CONSTRAINT_LE;
|
|
}
|
|
if( iGt>=0 ){
|
|
nRow = nRow / 2;
|
|
pIdxInfo->aConstraintUsage[iGt].argvIndex = iCons++;
|
|
idxNum |= SQLITE_INDEX_CONSTRAINT_GE;
|
|
}
|
|
pIdxInfo->estimatedRows = nRow;
|
|
pIdxInfo->estimatedCost = 3.0 * (double)nRow;
|
|
pIdxInfo->idxNum = idxNum;
|
|
}
|
|
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
static int createUnionVtab(sqlite3 *db){
|
|
static sqlite3_module unionModule = {
|
|
0, /* iVersion */
|
|
unionConnect,
|
|
unionConnect,
|
|
unionBestIndex, /* xBestIndex - query planner */
|
|
unionDisconnect,
|
|
unionDisconnect,
|
|
unionOpen, /* xOpen - open a cursor */
|
|
unionClose, /* xClose - close a cursor */
|
|
unionFilter, /* xFilter - configure scan constraints */
|
|
unionNext, /* xNext - advance a cursor */
|
|
unionEof, /* xEof - check for end of scan */
|
|
unionColumn, /* xColumn - read data */
|
|
unionRowid, /* xRowid - read data */
|
|
0, /* xUpdate */
|
|
0, /* xBegin */
|
|
0, /* xSync */
|
|
0, /* xCommit */
|
|
0, /* xRollback */
|
|
0, /* xFindMethod */
|
|
0, /* xRename */
|
|
};
|
|
|
|
return sqlite3_create_module(db, "unionvtab", &unionModule, 0);
|
|
}
|
|
|
|
#endif /* SQLITE_OMIT_VIRTUALTABLE */
|
|
|
|
#ifdef _WIN32
|
|
__declspec(dllexport)
|
|
#endif
|
|
int sqlite3_unionvtab_init(
|
|
sqlite3 *db,
|
|
char **pzErrMsg,
|
|
const sqlite3_api_routines *pApi
|
|
){
|
|
int rc = SQLITE_OK;
|
|
SQLITE_EXTENSION_INIT2(pApi);
|
|
#ifndef SQLITE_OMIT_VIRTUALTABLE
|
|
rc = createUnionVtab(db);
|
|
#endif
|
|
return rc;
|
|
}
|
|
|
|
#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_UNIONVTAB) */
|