Function convert_schema

cpp/deeplake_pg/table_am.cpp:487–592

}

void convert_schema(TupleDesc tupdesc)
{
    for (auto i = 0; i < tupdesc->natts; ++i) {
        Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
        // Skip dropped columns
        if (attr->attisdropped) {
            continue;
        }
        if (attr->atttypid == NUMERICOID && pg::treat_numeric_as_double) {
            constexpr int NUMERIC_PRECISION_SHIFT = 16;    // Bit shift for precision in typmod
            constexpr int NUMERIC_COMPONENT_MASK = 0xffff; // Mask for precision/scale extraction

            auto typmod = attr->atttypmod;
            auto precision = -1;
            auto scale = -1;
            if (typmod >= VARHDRSZ) {
                precision = ((typmod - VARHDRSZ) >> NUMERIC_PRECISION_SHIFT) & NUMERIC_COMPONENT_MASK;
                scale = (typmod - VARHDRSZ) & NUMERIC_COMPONENT_MASK;
            }
            // Convert to FLOAT8
            attr->atttypid = FLOAT8OID;
            attr->attlen = sizeof(float8);    // 8 bytes
            attr->attbyval = true;            // pass by value
            attr->attalign = TYPALIGN_DOUBLE; // 'd' - double alignment
            attr->atttypmod = -1;             // no type modifier for FLOAT8
            attr->attndims = 0;               // not an array
            const char* column_name = NameStr(attr->attname);
            if (precision >= 0) {
                elog(WARNING,
                     "Column '%s' converted from NUMERIC(%d,%d) to FLOAT8 - precision may be lost",
                     column_name,
                     precision,
                     scale);
            } else {
                elog(WARNING, "Column '%s' converted from NUMERIC to FLOAT8 - precision may be lost", column_name);
            }
        } else if (attr->atttypid == CHAROID || attr->atttypid == BPCHAROID) {
            // Convert CHAR and BPCHAR to VARCHAR
            attr->atttypid = VARCHAROID;
            attr->attlen = -1;             // variable length
            attr->attbyval = false;        // pass by reference
            attr->attalign = TYPALIGN_INT; // 'i' - int4 alignment
            attr->attstorage = TYPSTORAGE_EXTENDED;
            const char* column_name = NameStr(attr->attname);
            elog(WARNING,
                 "Column '%s' converted from CHAR/BPCHAR to VARCHAR as no fixed length string is supported",
                 column_name);
        }
        Oid base_typeid = pg::utils::get_base_type(attr->atttypid);
        // For domain types over arrays, adjust attndims since PostgreSQL doesn't preserve it
        const bool is_domain_over_array = (base_typeid != attr->atttypid && type_is_array(base_typeid));
        if (is_domain_over_array && attr->attndims == 0) {
            // Extract dimensionality from domain's CHECK constraint
            // Query pg_constraint and use pg_get_constraintdef() to get the constraint text
            auto query_str =
                fmt::format("SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE contypid = {} AND contype = 'c'",
                            attr->atttypid);
            pg::utils::spi_connector connector;