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Use without-rowid tables to reduce disk space use #2568

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Use without-rowid tables to reduce disk space use #2568

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10a6439
Use without-rowid tables to reduce disk space use
Codechicken Nov 27, 2025
a7ac2c6
Simplify selection of without rowid tables
Codechicken Nov 28, 2025
2482112
Fix formatting
Codechicken Dec 10, 2025
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19 changes: 18 additions & 1 deletion src/include/souffle/io/WriteStreamSQLite.h
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Original file line number Diff line number Diff line change
Expand Up @@ -199,14 +199,31 @@ class WriteStreamSQLite : public WriteStream {
void createRelationTable() {
std::stringstream createTableText;
createTableText << "CREATE TABLE IF NOT EXISTS '_" << relationName << "' (";
// 8 bytes per datum worst case + 1 byte per datum in header + 1 byte header length < ~1/20 DB page
// (4096 bytes) size See https://sqlite.org/withoutrowid.html#when_to_use_without_rowid and
// https://sqlite.org/fileformat2.html#record_format for justification
// 22*9+1 = 199 < 200
bool shouldUseWithoutRowid = (arity > 0 && arity < 23);
if (arity > 0) {
createTableText << "'0' INTEGER";
for (unsigned int i = 1; i < arity; i++) {
createTableText << ",'" << std::to_string(i) << "' ";
createTableText << "INTEGER";
}
if (shouldUseWithoutRowid) {
createTableText << ", PRIMARY KEY (";
createTableText << "'0'";
for (unsigned int i = 1; i < arity; i++) {
createTableText << ",'" << std::to_string(i) << "' ";
}
createTableText << ")";
}
}
if (shouldUseWithoutRowid) {
createTableText << ") WITHOUT ROWID;";
} else {
createTableText << ");";
}
createTableText << ");";
executeSQL(createTableText.str(), db);
executeSQL("DELETE FROM '_" + relationName + "';", db);
}
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