static RC LoadStat3(Context ctx, string dbName)
{
Debug.Assert(!ctx.Lookaside.Enabled);
if (sqlite3FindTable(ctx, "sqlite_stat3", dbName) == null)
{
return(RC.OK);
}
string sql = SysEx.Mprintf(ctx, "SELECT idx,count(*) FROM %Q.sqlite_stat3 GROUP BY idx", dbName); // Text of the SQL statement
if (!sql)
{
return(RC_NOMEM);
}
Vdbe stmt = null; // An SQL statement being run
RC rc = Vdbe.Prepare(ctx, sql, -1, stmt, 0); // Result codes from subroutines
C._tagfree(ctx, sql);
if (rc)
{
return(rc);
}
while (stmt.Step() == RC.ROW)
{
string indexName = (string)Vdbe.Column_Text(stmt, 0); // Index name
if (!indexName)
{
continue;
}
int samplesLength = Vdbe.Column_Int(stmt, 1); // Number of samples
Index idx = sqlite3FindIndex(ctx, indexName, dbName); // Pointer to the index object
if (!idx)
{
continue;
}
_assert(idx->Samples.length == 0);
idx.Samples.length = samplesLength;
idx.Samples.data = new IndexSample[samplesLength];
idx.AvgEq = idx.RowEsts[1];
if (!idx->Samples.data)
{
ctx->MallocFailed = true;
Vdbe.Finalize(stmt);
return(RC.NOMEM);
}
}
rc = Vdbe.Finalize(stmt);
if (rc)
{
return(rc);
}
sql = C._mtagprintf(ctx, "SELECT idx,neq,nlt,ndlt,sample FROM %Q.sqlite_stat3", dbName);
if (!sql)
{
return(RC.NOMEM);
}
rc = Vdbe.Prepare(ctx, sql, -1, &stmt, 0);
C._tagfree(ctx, sql);
if (rc)
{
return(rc);
}
Index prevIdx = null; // Previous index in the loop
int idxId = 0; // slot in pIdx->aSample[] for next sample
while (stmt.Step() == RC.ROW)
{
string indexName = (string)Vdbe.Column_Text(stmt, 0); // Index name
if (indexName == null)
{
continue;
}
Index idx = sqlite3FindIndex(ctx, indexName, dbName); // Pointer to the index object
if (idx == null)
{
continue;
}
if (idx == prevIdx)
{
idxId++;
}
else
{
prevIdx = idx;
idxId = 0;
}
Debug.Assert(idxId < idx.Samples.length);
IndexSample sample = idx.Samples[idxId]; // A slot in pIdx->aSample[]
sample.Eq = (tRowcnt)Vdbe.Column_Int64(stmt, 1);
sample.Lt = (tRowcnt)Vdbe.Column_Int64(stmt, 2);
sample.DLt = (tRowcnt)Vdbe.Column_Int64(stmt, 3);
if (idxId == idx.Samples.length - 1)
{
tRowcnt sumEq; // Sum of the nEq values
if (sample.DLt > 0)
{
for (int i = 0, sumEq = 0; i <= idxId - 1; i++)
{
sumEq += idx.Samples[i].Eq;
}
idx.AvgEq = (sample.Lt - sumEq) / sample.DLt;
}
if (idx.AvgEq <= 0)
{
idx.AvgEq = 1;
}
}
TYPE type = Vdbe.Column_Type(stmt, 4); // Datatype of a sample
sample.Type = type;
switch (type)
{
case TYPE.INTEGER:
{
sample.u.I = Vdbe.Column_Int64(stmt, 4);
break;
}
case TYPE.FLOAT:
{
sample.u.R = Vdbe.Column_Double(stmt, 4);
break;
}
case TYPE.NULL:
{
break;
}
default: Debug.Assert(type == TYPE.TEXT || type == TYPE.BLOB);
{
string z = (string)(type == TYPE_BLOB ? Vdbe.Column_Blob(stmt, 4) : Vdbe.Column_Text(stmt, 4));
int n = (z ? Vdbe.Column_Bytes(stmt, 4) : 0);
sample.Bytes = n;
if (n < 1)
{
sample.u.Z = null;
}
else
{
sample.u.Z = C._tagalloc(ctx, n);
if (sample->u.Z == null)
{
ctx.MallocFailed = true;
Vdbe.Finalize(stmt);
return(RC.NOMEM);
}
Buffer.BlockCopy(sample.u.Z, z, n);
}
}
}
}
return(Vdbe.Finalize(stmt));
}
