**
** This file contains an implementation of the "dbstat" virtual table.
**
-** The dbstat virtual table is used to extract low-level formatting
+** The dbstat virtual table is used to extract low-level storage
** information from an SQLite database in order to implement the
** "sqlite3_analyzer" utility. See the ../tool/spaceanal.tcl script
** for an example implementation.
**
** '/1c2/000/' // Left-most child of 451st child of root
*/
-#define VTAB_SCHEMA \
- "CREATE TABLE xx( " \
- " name TEXT, /* Name of table or index */" \
- " path TEXT, /* Path to page from root */" \
- " pageno INTEGER, /* Page number */" \
- " pagetype TEXT, /* 'internal', 'leaf' or 'overflow' */" \
- " ncell INTEGER, /* Cells on page (0 for overflow) */" \
- " payload INTEGER, /* Bytes of payload on this page */" \
- " unused INTEGER, /* Bytes of unused space on this page */" \
- " mx_payload INTEGER, /* Largest payload size of all cells */" \
- " pgoffset INTEGER, /* Offset of page in file */" \
- " pgsize INTEGER, /* Size of the page */" \
- " schema TEXT HIDDEN /* Database schema being analyzed */" \
+#define VTAB_SCHEMA \
+ "CREATE TABLE xx( " \
+ " name TEXT," /* 0 Name of table or index */ \
+ " path TEXT," /* 1 Path to page from root */ \
+ " pageno INTEGER," /* 2 Page number */ \
+ " pagetype TEXT," /* 3 'internal', 'leaf' or 'overflow' */ \
+ " ncell INTEGER," /* 4 Cells on page (0 for overflow) */ \
+ " payload INTEGER," /* 5 Bytes of payload on this page */ \
+ " unused INTEGER," /* 6 Bytes of unused space on this page */ \
+ " mx_payload INTEGER," /* 7 Largest payload size of all cells */ \
+ " pgoffset INTEGER," /* 8 Offset of page in file */ \
+ " pgsize INTEGER," /* 9 Size of the page */ \
+ " schema TEXT HIDDEN," /* 10 Database schema being analyzed */ \
+ " aggregate BOOLEAN HIDDEN" /* 11 aggregate info for each table */ \
");"
-
+/* Forward reference to data structured used in this module */
typedef struct StatTable StatTable;
typedef struct StatCursor StatCursor;
typedef struct StatPage StatPage;
typedef struct StatCell StatCell;
+/* Size information for a single cell within a btree page */
struct StatCell {
int nLocal; /* Bytes of local payload */
u32 iChildPg; /* Child node (or 0 if this is a leaf) */
int iOvfl; /* Iterates through aOvfl[] */
};
+/* Size information for a single btree page */
struct StatPage {
- u32 iPgno;
- DbPage *pPg;
- int iCell;
+ u32 iPgno; /* Page number */
+ DbPage *pPg; /* Page content */
+ int iCell; /* Current cell */
char *zPath; /* Path to this page */
int nUnused; /* Number of unused bytes on page */
StatCell *aCell; /* Array of parsed cells */
u32 iRightChildPg; /* Right-child page number (or 0) */
- int nMxPayload; /* Largest payload of any cell on this page */
+ int nMxPayload; /* Largest payload of any cell on the page */
};
+/* The cursor for scanning the dbstat virtual table */
struct StatCursor {
- sqlite3_vtab_cursor base;
+ sqlite3_vtab_cursor base; /* base class. MUST BE FIRST! */
sqlite3_stmt *pStmt; /* Iterates through set of root pages */
int isEof; /* After pStmt has returned SQLITE_DONE */
int iDb; /* Schema used for this query */
+ int isAgg; /* Aggregate results for each table */
- StatPage aPage[32];
+ StatPage aPage[32]; /* Pages in path to current page */
int iPage; /* Current entry in aPage[] */
/* Values to return. */
int szPage; /* Value of 'pgSize' column */
};
+/* An instance of the DBSTAT virtual table */
struct StatTable {
- sqlite3_vtab base;
- sqlite3 *db;
+ sqlite3_vtab base; /* base class. MUST BE FIRST! */
+ sqlite3 *db; /* Database connection that owns this vtab */
int iDb; /* Index of database to analyze */
};
#endif
/*
-** Connect to or create a statvfs virtual table.
+** Connect to or create a new DBSTAT virtual table.
*/
static int statConnect(
sqlite3 *db,
}
/*
-** Disconnect from or destroy a statvfs virtual table.
+** Disconnect from or destroy the DBSTAT virtual table.
*/
static int statDisconnect(sqlite3_vtab *pVtab){
sqlite3_free(pVtab);
}
/*
-** There is no "best-index". This virtual table always does a linear
-** scan. However, a schema=? constraint should cause this table to
-** operate on a different database schema, so check for it.
+** Compute the best query strategy and return the result in idxNum.
**
-** idxNum is normally 0, but will be 1 if a schema=? constraint exists.
+** idxNum-Bit Meaning
+** ---------- ----------------------------------------------
+** 0x01 There is a schema=? term in the WHERE clause
+** 0x02 There is a name=? term in the WHERE clause
+** 0x04 There is an aggregate=? term in the WHERE clause
+** 0x08 Output should be ordered by name and path
*/
static int statBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
int i;
+ int iSchema = -1;
+ int iName = -1;
+ int iAgg = -1;
/* Look for a valid schema=? constraint. If found, change the idxNum to
** 1 and request the value of that constraint be sent to xFilter. And
** used.
*/
for(i=0; i<pIdxInfo->nConstraint; i++){
- if( pIdxInfo->aConstraint[i].iColumn!=10 ) continue;
- if( pIdxInfo->aConstraint[i].usable==0 ) return SQLITE_CONSTRAINT;
if( pIdxInfo->aConstraint[i].op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
- pIdxInfo->idxNum = 1;
- pIdxInfo->estimatedCost = 1.0;
- pIdxInfo->aConstraintUsage[i].argvIndex = 1;
- pIdxInfo->aConstraintUsage[i].omit = 1;
- break;
+ if( pIdxInfo->aConstraint[i].usable==0 ){
+ /* Force DBSTAT table should always be the right-most table in a join */
+ return SQLITE_CONSTRAINT;
+ }
+ switch( pIdxInfo->aConstraint[i].iColumn ){
+ case 0: { /* name */
+ iName = i;
+ break;
+ }
+ case 10: { /* schema */
+ iSchema = i;
+ break;
+ }
+ case 11: { /* aggregate */
+ iAgg = i;
+ break;
+ }
+ }
}
-
+ i = 0;
+ if( iSchema>=0 ){
+ pIdxInfo->aConstraintUsage[iSchema].argvIndex = ++i;
+ pIdxInfo->aConstraintUsage[iSchema].omit = 1;
+ pIdxInfo->idxNum |= 0x01;
+ }
+ if( iName>=0 ){
+ pIdxInfo->aConstraintUsage[iName].argvIndex = ++i;
+ pIdxInfo->aConstraintUsage[iName].omit = 1;
+ pIdxInfo->idxNum |= 0x02;
+ }
+ if( iAgg>=0 ){
+ pIdxInfo->aConstraintUsage[iAgg].argvIndex = ++i;
+ pIdxInfo->aConstraintUsage[iAgg].omit = 1;
+ pIdxInfo->idxNum |= 0x04;
+ }
+ pIdxInfo->estimatedCost = 1.0;
/* Records are always returned in ascending order of (name, path).
** If this will satisfy the client, set the orderByConsumed flag so that
)
){
pIdxInfo->orderByConsumed = 1;
+ pIdxInfo->idxNum |= 0x08;
}
return SQLITE_OK;
return SQLITE_OK;
}
-static void getLocalPayload(
+/*
+** For a single cell on a btree page, compute the number of bytes of
+** content (payload) stored on that page. That is to say, compute the
+** number of bytes of content not found on overflow pages.
+*/
+static int getLocalPayload(
int nUsable, /* Usable bytes per page */
u8 flags, /* Page flags */
- int nTotal, /* Total record (payload) size */
- int *pnLocal /* OUT: Bytes stored locally */
+ int nTotal /* Total record (payload) size */
){
int nLocal;
int nMinLocal;
nLocal = nMinLocal + (nTotal - nMinLocal) % (nUsable - 4);
if( nLocal>nMaxLocal ) nLocal = nMinLocal;
- *pnLocal = nLocal;
+ return nLocal;
}
static int statDecodePage(Btree *pBt, StatPage *p){
iOff += sqlite3GetVarint(&aData[iOff], &dummy);
}
if( nPayload>(u32)p->nMxPayload ) p->nMxPayload = nPayload;
- getLocalPayload(nUsable, p->flags, nPayload, &nLocal);
+ nLocal = getLocalPayload(nUsable, p->flags, nPayload);
if( nLocal<0 ) goto statPageIsCorrupt;
pCell->nLocal = nLocal;
assert( nPayload>=(u32)nLocal );
return pCsr->isEof;
}
+/* Initialize a cursor according to the query plan idxNum using the
+** arguments in argv[0]. See statBestIndex() for a description of the
+** meaning of the bits in idxNum.
+*/
static int statFilter(
sqlite3_vtab_cursor *pCursor,
int idxNum, const char *idxStr,
){
StatCursor *pCsr = (StatCursor *)pCursor;
StatTable *pTab = (StatTable*)(pCursor->pVtab);
- char *zSql;
- int rc = SQLITE_OK;
+ sqlite3_str *pSql; /* Query of btrees to analyze */
+ char *zSql; /* String value of pSql */
+ int iArg = 0; /* Count of argv[] parameters used so far */
+ int rc = SQLITE_OK; /* Result of this operation */
+ const char *zName = 0; /* Only provide analysis of this table */
- if( idxNum==1 ){
- const char *zDbase = (const char*)sqlite3_value_text(argv[0]);
+ statResetCsr(pCsr);
+ sqlite3_finalize(pCsr->pStmt);
+ pCsr->pStmt = 0;
+ if( idxNum & 0x01 ){
+ /* schema=? constraint is present. Get its value */
+ const char *zDbase = (const char*)sqlite3_value_text(argv[iArg++]);
pCsr->iDb = sqlite3FindDbName(pTab->db, zDbase);
if( pCsr->iDb<0 ){
sqlite3_free(pCursor->pVtab->zErrMsg);
}else{
pCsr->iDb = pTab->iDb;
}
- statResetCsr(pCsr);
- sqlite3_finalize(pCsr->pStmt);
- pCsr->pStmt = 0;
- zSql = sqlite3_mprintf(
- "SELECT 'sqlite_master' AS name, 1 AS rootpage, 'table' AS type"
- " UNION ALL "
- "SELECT name, rootpage, type"
- " FROM \"%w\".sqlite_master WHERE rootpage!=0"
- " ORDER BY name", pTab->db->aDb[pCsr->iDb].zDbSName);
+ if( idxNum & 0x02 ){
+ /* name=? constraint is present */
+ zName = (const char*)sqlite3_value_text(argv[iArg++]);
+ }
+ if( idxNum & 0x04 ){
+ /* aggregate=? constraint is present */
+ pCsr->isAgg = sqlite3_value_double(argv[iArg++])!=0.0;
+ }else{
+ pCsr->isAgg = 0;
+ }
+ pSql = sqlite3_str_new(pTab->db);
+ sqlite3_str_appendf(pSql,
+ "SELECT * FROM ("
+ "SELECT 'sqlite_master' AS name,1 AS rootpage,'table' AS type"
+ " UNION ALL "
+ "SELECT name,rootpage,type"
+ " FROM \"%w\".sqlite_master WHERE rootpage!=0)",
+ pTab->db->aDb[pCsr->iDb].zDbSName);
+ if( zName ){
+ sqlite3_str_appendf(pSql, "WHERE name=%Q", zName);
+ }
+ if( idxNum & 0x08 ){
+ sqlite3_str_appendf(pSql, " ORDER BY name");
+ }
+ zSql = sqlite3_str_finish(pSql);
if( zSql==0 ){
return SQLITE_NOMEM_BKPT;
}else{
case 9: /* pgsize */
sqlite3_result_int(ctx, pCsr->szPage);
break;
- default: { /* schema */
+ case 10: { /* schema */
sqlite3 *db = sqlite3_context_db_handle(ctx);
int iDb = pCsr->iDb;
sqlite3_result_text(ctx, db->aDb[iDb].zDbSName, -1, SQLITE_STATIC);
break;
}
+ default: { /* aggregate */
+ sqlite3_result_int(ctx, pCsr->isAgg);
+ break;
+ }
}
return SQLITE_OK;
}
projects / thirdparty / sqlite.git / commitdiff
