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Merge pull request #73140 from ClickHouse/backport/24.10/71396

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Backport #71396 to 24.10: Fix: ERROR: column "attgenerated" does not exist for old PostgreSQL
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Kseniia Sumarokova 2024-12-16 12:46:49 +01:00 committed by GitHub
commit 0b0de9e90f
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1 changed files with 9 additions and 2 deletions
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11
src/Databases/PostgreSQL/fetchPostgreSQLTableStructure.cpp
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@ -307,6 +307,13 @@ PostgreSQLTableStructure fetchPostgreSQLTableStructure(
if (!columns.empty())
columns_part = fmt::format(" AND attname IN ('{}')", boost::algorithm::join(columns, "','"));
/// Bypassing the error of the missing column `attgenerated` in the system table `pg_attribute` for PostgreSQL versions below 12.
/// This trick involves executing a special query to the DBMS in advance to obtain the correct line with comment /// if column has GENERATED.
/// The result of the query will be the name of the column `attgenerated` or an empty string declaration for PostgreSQL version 11 and below.
/// This change does not degrade the function's performance but restores support for older versions and fix ERROR: column "attgenerated" does not exist.
pqxx::result gen_result{tx.exec("select case when current_setting('server_version_num')::int < 120000 then '''''' else 'attgenerated' end as generated")};
std::string generated = gen_result[0][0].as<std::string>();
std::string query = fmt::format(
"SELECT attname AS name, " /// column name
"format_type(atttypid, atttypmod) AS type, " /// data type
@ -315,11 +322,11 @@ PostgreSQLTableStructure fetchPostgreSQLTableStructure(
"atttypid as type_id, "
"atttypmod as type_modifier, "
"attnum as att_num, "
"attgenerated as generated " /// if column has GENERATED
"{} as generated " /// if column has GENERATED
"FROM pg_attribute "
"WHERE attrelid = (SELECT oid FROM pg_class WHERE {}) {}"
"AND NOT attisdropped AND attnum > 0 "
"ORDER BY attnum ASC", where, columns_part);
"ORDER BY attnum ASC", generated, where, columns_part); /// Now we use variable `generated` to form query string. End of trick.
auto postgres_table_with_schema = postgres_schema.empty() ? postgres_table : doubleQuoteString(postgres_schema) + '.' + doubleQuoteString(postgres_table);
table.physical_columns = readNamesAndTypesList(tx, postgres_table_with_schema, query, use_nulls, false);