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org.tentackle.sql.backends.Postgres Maven / Gradle / Ivy
/*
* Tentackle - https://tentackle.org
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package org.tentackle.sql.backends;
import org.tentackle.common.Service;
import org.tentackle.common.TentackleRuntimeException;
import org.tentackle.sql.Backend;
import org.tentackle.sql.BackendPreparedStatement;
import org.tentackle.sql.MigrationStrategy;
import org.tentackle.sql.NonStandardCommons;
import org.tentackle.sql.SqlType;
import org.tentackle.sql.metadata.ColumnMetaData;
import org.tentackle.sql.metadata.IndexColumnMetaData;
import org.tentackle.sql.metadata.IndexMetaData;
import org.tentackle.sql.metadata.PostgresColumnMetaData;
import org.tentackle.sql.metadata.PostgresIndexColumnMetaData;
import org.tentackle.sql.metadata.PostgresIndexMetaData;
import org.tentackle.sql.metadata.TableMetaData;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Types;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Objects;
import java.util.Set;
/**
* Backend for Postgres.
*
* @author harald
*/
@Service(Backend.class)
public class Postgres extends AbstractSql92Backend {
/** postgres' default schema. */
public static final String DEFAULT_SCHEMA = "public";
/** LIMIT string. */
public static final String SQL_LIMIT = " LIMIT ";
/** OFFSET string. */
public static final String SQL_OFFSET = " OFFSET ";
/** LIMIT ? string. */
public static final String SQL_LIMIT_PAR = SQL_LIMIT + SQL_PAR;
/** OFFSET ? string. */
public static final String SQL_OFFSET_PAR = SQL_OFFSET + SQL_PAR;
/** array of additional reserved words. */
public static final String[] RESERVED_WORDS_PG = new String[] {
"TEXT"
};
private static final String[] RESERVED_SCHEMAS = {
"information_schema",
"pg_catalog",
"pg_temp_1",
"pg_toast",
"pg_toast_temp_1"
};
/** set of reserved words (built only once). */
private static Set reservedWords;
@Override
public synchronized Set getReservedWords() {
if (reservedWords == null) {
reservedWords = new HashSet<>(super.getReservedWords());
reservedWords.addAll(Arrays.asList(RESERVED_WORDS_PG));
}
return reservedWords;
}
@Override
public boolean isMatchingUrl(String url) {
return url.contains(":postgresql");
}
@Override
public String getName() {
return "PostgreSQL";
}
@Override
public String getDriverClassName() {
return "org.postgresql.Driver";
}
@Override
public String getBackendId(Connection connection) {
try (Statement stmt = connection.createStatement()) {
ResultSet rs = stmt.executeQuery("select pg_backend_pid()");
if (rs.next()) {
return "PID-" + rs.getString(1);
}
return null;
}
catch (SQLException ex) {
throw new TentackleRuntimeException("cannot determine backend id", ex);
}
}
@Override
public boolean isReleaseSavepointSupported() {
return true;
}
@Override
public boolean isReservedSchemaName(String name) {
for (String reserved_schema: RESERVED_SCHEMAS) {
if (reserved_schema.equalsIgnoreCase(name)) {
return true;
}
}
return false;
}
@Override
public boolean isTransientTransactionException(SQLException ex) {
return super.isTransientTransactionException(ex) ||
// deadlock detected, lock not available
isExceptionStateMatching(ex, "40P01", "55P03");
}
@Override
public boolean isClobSupported() {
return false; // use TEXT instead
}
@Override
public boolean isFilteredIndexSupported() {
return true;
}
@Override
public boolean isFunctionBasedIndexSupported() {
return true;
}
@Override
public boolean needTxForFetchsize() {
return true;
}
@Override
public boolean needAliasForSubselect() {
return true;
}
@Override
public void buildSelectSql(StringBuilder sqlBuilder, boolean writeLock, int limit, int offset) {
sqlBuilder.insert(0, SQL_SELECT);
if (writeLock) {
sqlBuilder.append(SQL_FOR_UPDATE);
}
if (limit > 0) {
sqlBuilder.append(SQL_LIMIT_PAR);
}
if (offset > 0) {
sqlBuilder.append(SQL_OFFSET_PAR);
}
}
@Override
public int setLeadingSelectParameters(BackendPreparedStatement stmt, int limit, int offset) {
return 1;
}
@Override
public int setTrailingSelectParameters(BackendPreparedStatement stmt, int index, int limit, int offset) {
if (limit > 0) {
stmt.setInt(index++, limit);
}
if (offset > 0) {
stmt.setInt(index++, offset);
}
return index;
}
@Override
public ColumnMetaData createColumnMetaData(TableMetaData tableMetaData) {
return new PostgresColumnMetaData(tableMetaData);
}
@Override
public IndexMetaData createIndexMetaData(TableMetaData tableMetaData) {
return new PostgresIndexMetaData(tableMetaData);
}
@Override
public IndexColumnMetaData createIndexColumnMetaData(IndexMetaData indexMetaData) {
return new PostgresIndexColumnMetaData(indexMetaData);
}
@Override
public int getMaxSize(SqlType sqlType) {
if (sqlType == SqlType.DECIMAL) {
return 999;
}
return super.getMaxSize(sqlType);
}
@Override
public int getDefaultSize(SqlType sqlType) {
if (sqlType == SqlType.VARCHAR) {
return 0;
}
return super.getDefaultSize(sqlType);
}
@Override
public String getDefaultSchema() {
return DEFAULT_SCHEMA;
}
@Override
public SqlType[] jdbcTypeToSqlType(int jdbcType, int size, int scale) {
switch(jdbcType) {
case Types.TINYINT:
case Types.SMALLINT:
return new SqlType[] { SqlType.TINYINT, SqlType.SMALLINT };
case Types.VARCHAR:
case Types.LONGVARCHAR:
case Types.NVARCHAR:
case Types.LONGNVARCHAR:
case Types.CLOB:
case Types.NCLOB:
return new SqlType[] { SqlType.VARCHAR, SqlType.CLOB };
default:
return super.jdbcTypeToSqlType(jdbcType, size, scale);
}
}
@Override
public String sqlTypeToString(SqlType sqlType, int size) {
switch(sqlType) {
case BIT:
return TYPE_BOOL;
case TINYINT:
case SMALLINT:
return TYPE_INT2;
case INTEGER:
return TYPE_INT4;
case BIGINT:
return TYPE_INT8;
case FLOAT:
return TYPE_FLOAT4;
case DOUBLE:
return TYPE_FLOAT8;
case DECIMAL:
return TYPE_DECIMAL;
case CHAR:
return TYPE_CHAR_1;
case VARCHAR:
return size == 0 ? TYPE_TEXT : TYPE_VARCHAR;
case DATE:
return TYPE_DATE;
case TIME:
return TYPE_TIME;
case TIMESTAMP:
return TYPE_TIMESTAMP;
case BLOB:
return TYPE_BYTEA;
case CLOB:
return TYPE_TEXT;
default:
return super.sqlTypeToString(sqlType, size);
}
}
@Override
public boolean supportsSequences() {
return true;
}
@Override
public String sqlNextFromSequene(String name) {
return "SELECT NEXTVAL('" + name + "')";
}
@Override
public String sqlCreateTableComment(String tableName, String comment) {
return NonStandardCommons.sqlCreateCommentOnTable(this, tableName, comment);
}
@Override
public String sqlCreateColumnComment(String tableName, String columnName, String comment) {
return NonStandardCommons.sqlCreateCommentOnColumn(this, tableName, columnName, comment);
}
@Override
public String sqlAlterColumnType(String tableName, String columnName, String comment, SqlType sqlType,
int size, int scale, boolean nullable, Object defaultValue) {
return SQL_ALTER_TABLE + tableName +
SQL_ALTER_COLUMN +
columnName +
" TYPE " +
// nullable = true -> Postgres needs separate SET NOT NULL
// default = null -> Postgres needs separate SET DEFAULT
columnTypeNullDefaultToString(columnName, sqlType, size, scale, true, null) +
";\n";
}
@Override
public String sqlAlterColumnNullConstraint(String tableName, String columnName, boolean nullable) {
StringBuilder buf = new StringBuilder(SQL_ALTER_TABLE);
buf.append(tableName);
buf.append(SQL_ALTER_COLUMN);
buf.append(columnName);
if (nullable) {
buf.append(" DROP");
}
else {
buf.append(" SET");
}
buf.append(" NOT NULL;\n");
return buf.toString();
}
@Override
public String toInternalType(String sqlTypeName) {
String typeName = sqlTypeName.toLowerCase(); // postgres is case-sensitive internally and needs lowercase
// char(1) is okay for SQL scripts, but not a valid postgres type
int ndx = typeName.indexOf('(');
if (ndx >= 0) {
typeName = typeName.substring(0, ndx); // cut (xxx)
}
return typeName;
}
@Override
public boolean isArrayOperatorSupported(String operator) {
return SQL_ARRAY_ALL.equals(operator) || SQL_ARRAY_ANY.equals(operator);
}
@Override
public MigrationStrategy[] getMigrationStrategy(ColumnMetaData column, String columnName, String comment,
SqlType sqlType, int size, int scale, boolean nullable, Object defaultValue) {
List strategies = new ArrayList<>();
int maxSize = getMaxSize(sqlType);
boolean nameChanged = !column.getColumnName().equalsIgnoreCase(columnName);
boolean commentChanged = !Objects.equals(column.getComment(), comment);
boolean defaultChanged = !isDefaultEqual(column, sqlType, defaultValue);
boolean nullChanged = column.isNullable() != nullable;
boolean typeChanged = !column.matchesSqlType(sqlType);
boolean sizeChanged = maxSize != -1 &&
(size > column.getSize() || // model size increased
// or changed from VARCHAR(x) to TEXT
size == 0 && (sqlType == SqlType.VARCHAR || sqlType == SqlType.CLOB) &&
column.getSize() > 0 && column.getSize() != Integer.MAX_VALUE);
boolean sizeWarning = maxSize != -1 && size != 0 && size < column.getSize();
boolean scaleChanged = scale > column.getScale(); // smaller model scale is allowed
boolean scaleWarning = maxSize != -1 && scale < column.getScale();
// ideal backend: name, comment, null and default can be changed separately from type,size and scale
if (nameChanged) {
strategies.add(MigrationStrategy.NAME); // comes first because next steps refer to the new column name
}
if (typeChanged || sizeChanged || scaleChanged) {
strategies.add(MigrationStrategy.TYPE);
}
else if (sizeWarning || scaleWarning) {
strategies.add(MigrationStrategy.TYPE_WARNING); // only as comment
}
if (nullChanged) {
strategies.add(MigrationStrategy.NULL);
}
if (defaultChanged) {
strategies.add(MigrationStrategy.DEFAULT);
}
if (commentChanged) {
strategies.add(MigrationStrategy.COMMENT);
}
return strategies.toArray(new MigrationStrategy[0]);
}
@Override
protected String extractWhereClause(String sql, int whereOffset) {
sql = super.extractWhereClause(sql, whereOffset);
int ndx = sql.lastIndexOf(SQL_LIMIT);
if (ndx >= 0) {
sql = sql.substring(0, ndx);
}
ndx = sql.lastIndexOf(SQL_OFFSET);
if (ndx >= 0) {
sql = sql.substring(0, ndx);
}
return sql;
}
@Override
protected boolean isDropIfExistsSupported() {
return true;
}
}
