WillAyd commented on code in PR #577:
URL: https://github.com/apache/arrow-adbc/pull/577#discussion_r1183886626
##########
c/driver/postgresql/connection.cc:
##########
@@ -47,7 +49,80 @@ AdbcStatusCode PostgresConnection::GetTableSchema(const
char* catalog,
const char* table_name,
struct ArrowSchema* schema,
struct AdbcError* error) {
- return ADBC_STATUS_NOT_IMPLEMENTED;
+ AdbcStatusCode final_status = ADBC_STATUS_OK;
+ struct StringBuilder query = {0};
+ if (StringBuilderInit(&query, /*initial_size=*/256) != 0) return
ADBC_STATUS_INTERNAL;
+
+ if (StringBuilderAppend(
+ &query, "%s",
+ "SELECT attname, atttypid "
+ "FROM pg_catalog.pg_class AS cls "
+ "INNER JOIN pg_catalog.pg_attribute AS attr ON cls.oid =
attr.attrelid "
+ "INNER JOIN pg_catalog.pg_type AS typ ON attr.atttypid = typ.oid "
+ "WHERE attr.attnum >= 0 AND cls.oid = '") != 0)
+ return ADBC_STATUS_INTERNAL;
+
+ if (db_schema != nullptr) {
+ char* schema = PQescapeIdentifier(conn_, db_schema, strlen(db_schema));
+ if (schema == NULL) {
+ SetError(error, "%s%s", "Faled to escape schema: ",
PQerrorMessage(conn_));
+ return ADBC_STATUS_INVALID_ARGUMENT;
+ }
+
+ int ret = StringBuilderAppend(&query, "%s%s", schema, ".");
+ PQfreemem(schema);
+
+ if (ret != 0) return ADBC_STATUS_INTERNAL;
+ }
+
+ char* table = PQescapeIdentifier(conn_, table_name, strlen(table_name));
+ if (table == NULL) {
+ SetError(error, "%s%s", "Failed to escape table: ", PQerrorMessage(conn_));
+ return ADBC_STATUS_INVALID_ARGUMENT;
+ }
+
+ int ret = StringBuilderAppend(&query, "%s%s", table_name,
"'::regclass::oid");
+ PQfreemem(table);
+
+ if (ret != 0) return ADBC_STATUS_INTERNAL;
+
+ pg_result* result = PQexec(conn_, query.buffer);
+ StringBuilderReset(&query);
+
+ ExecStatusType pq_status = PQresultStatus(result);
+ if (pq_status == PGRES_TUPLES_OK) {
+ int num_rows = PQntuples(result);
+ ArrowSchemaInit(schema);
+ CHECK_NA(INTERNAL, ArrowSchemaSetTypeStruct(schema, num_rows), error);
+
+ ArrowError na_error;
+ for (int row = 0; row < num_rows; row++) {
+ const char* colname = PQgetvalue(result, row, 0);
+ const Oid pg_oid = static_cast<uint32_t>(
+ std::strtol(PQgetvalue(result, row, 1), /*str_end=*/nullptr,
/*base=*/10));
+
+ PostgresType pg_type;
+ if (type_resolver_->Find(pg_oid, &pg_type, &na_error) != NANOARROW_OK) {
Review Comment:
Have to excuse my poor C++, but I'm guessing this is as simple as a
`PgResultHelper` class with an `execute` method that has `PQclear` in its
destructor?
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