mysql转postgresql

痛定思痛。 2021-11-05 11:34 321阅读 0赞

使用步骤

1.  使用mysqldump dump出PG兼容的MySQL建表语句（修改下面语句中的databasename和dumpfile.sql），此处dump语句很重要，一定要转为PG兼容的建表语句：
    
    `mysqldump --opt --compatible=postgresql --default-character-set=utf8 -d databasename -r dumpfile.sql -u username -p`
2.  执行转换脚本，dumpfile.sql和adbforpg.sql填写真实的值
    
    `python db_converter.py dumpfile.sql adbforpg.sql`

adbforpg.sql是转换后的ADB for PG的建表语句，如果需要有需改需求，可以直接在文件中进行修改。重点要关注一下分布列的选择，默认选择MySQL表中的主键作为分布列，如果MySQL表结构中无主键，请手动修改选择分布列。

# encoding=utf8
    # !/usr/bin/env python
    
    """
    Fixes a MySQL dump made with the right format so it can be directly
    imported to a new PostgreSQL database.
    
    Dump using:
    mysqldump --opt --compatible=postgresql --default-character-set=utf8 -d databasename -r dumpfile.sql -u root -p
    """
    
    import re
    import sys
    import os
    import time
    import subprocess
    
    
    reload(sys)
    sys.setdefaultencoding('utf8')
    
    
    def parse(input_filename, output_filename):
        "Feed it a file, and it'll output a fixed one"
    
        # State storage
        if input_filename == "-":
            num_lines = -1
        else:
            num_lines = int(subprocess.check_output(["wc", "-l", input_filename]).strip().split()[0])
        tables = {}
        current_table = None
        creation_lines = []
        cast_lines = []
        index_lines = []
        comment_line = []
        num_inserts = 0
        started = time.time()
        primary_key = None
    
        # Open output file and write header. Logging file handle will be stdout
        # unless we're writing output to stdout, in which case NO PROGRESS FOR YOU.
        if output_filename == "-":
            output = sys.stdout
            logging = open(os.devnull, "w")
        else:
            output = open(output_filename, "w")
            logging = sys.stdout
    
        if input_filename == "-":
            input_fh = sys.stdin
        else:
            input_fh = open(input_filename)
    
        output.write("-- Converted by db_converter\n")
        output.write("START TRANSACTION;\n")
        # output.write("SET standard_conforming_strings=off;\n")
        # output.write("SET escape_string_warning=off;\n")
        # output.write("SET CONSTRAINTS ALL DEFERRED;\n\n")
    
        for i, line in enumerate(input_fh):
            time_taken = time.time() - started
            percentage_done = (i + 1) / float(num_lines)
            secs_left = (time_taken / percentage_done) - time_taken
            logging.write("\rLine %i (of %s: %.2f%%) [%s tables] [%s inserts] [ETA: %i min %i sec]" % (
                i + 1,
                num_lines,
                ((i + 1) / float(num_lines)) * 100,
                len(tables),
                num_inserts,
                secs_left // 60,
                secs_left % 60,
            ))
            logging.flush()
            line = line.decode("utf8").strip().replace(r"\\", "WUBWUBREALSLASHWUB").replace(r"\'", "''").replace("WUBWUBREALSLASHWUB", r"\\")
            # Ignore comment lines
            if line.startswith("--") or line.startswith("/*") or line.startswith("LOCK TABLES") or line.startswith("DROP TABLE") or line.startswith("UNLOCK TABLES") or not line:
                continue
    
            # Outside of anything handling
            if current_table is None:
                # Start of a table creation statement?
                if line.startswith("CREATE TABLE"):
                    current_table = line.split('"')[1].lower()
                    tables[current_table] = {"columns": []}
                    creation_lines = []
                else:
                    print "\n ! Unknown line in main body: %s" % line
    
            # Inside-create-statement handling
            else:
                # Is it a column?
                if line.startswith('"'):
                    useless, name, definition = line.strip(",").split('"', 2)
                    name = name.lower()
                    try:
                        type, extra = definition.strip().split(" ", 1)
    
                    except ValueError:
                        type = definition.strip()
                        extra = ""
                    extra = re.sub("CHARACTER SET [\w\d]+\s*", "", extra)
                    extra = re.sub("COLLATE [\w\d]+\s*", "", extra.replace("'0000-00-00 00:00:00'", "NULL"))
                    if extra.find("COMMENT '") > -1:
                        pattern = re.compile("COMMENT '(.*)'")
                        comment_line.append(u"COMMENT ON COLUMN \"%s\".\"%s\" is '%s'" % (current_table, name, pattern.findall(extra)[0]))
                        extra = re.sub("COMMENT '.*'", "", extra)
    
                    # See if it needs type conversion
                    final_type = None
                    if type.startswith("tinyint("):
                        type = "smallint"
                    elif type.startswith("int(") and extra.startswith("unsigned"):
                        type = "bigint"
                    elif type.startswith("int("):
                        type = "integer"
                    elif type.startswith("smallint(") and extra.startswith("unsigned"):
                        type = "integer"
                    elif type.startswith("smallint("):
                        type = "smallint"
                    elif type.startswith("mediumint("):
                        type = "integer"
                    elif type.startswith("bigint("):
                        type = "bigint"
                    elif type.startswith("year"):
                        type = "integer"
    
                    elif type == "longtext":
                        type = "text"
                    elif type == "mediumtext":
                        type = "text"
                    elif type == "tinytext":
                        type = "text"
                    elif type.startswith("varchar("):
                        size = int(type.split("(")[1].split(")")[0])
                        type = "varchar(%s)" % (size * 2)
    
                    elif type == "datetime":
                        type = "timestamp without time zone"
                    elif type == "timestamp":
                        type = "timestamp with time zone"
    
                    elif type == "double":
                        type = "double precision"
                    elif type.startswith("float"):
                        type = "real"
                    elif type.endswith("blob"):
                        type = "bytea"
                    elif type.endswith("binary"):
                        type = "bytea"
                    elif type.startswith("enum(") or type.startswith("set("):
                        type = "varchar"
    
                    elif type.startswith("linestring"):
                        type = "path"
                    elif type.startswith("point"):
                        type = "point"
    
                    extra = extra.replace("unsigned", "")
    
                    if final_type:
                        cast_lines.append(
                            "ALTER TABLE \"%s\" ALTER COLUMN \"%s\" DROP DEFAULT, ALTER COLUMN \"%s\" TYPE %s USING CAST(\"%s\" as %s)" % (current_table, name, name, final_type, name, final_type))
                    creation_lines.append('"%s" %s %s' % (name, type, extra))
                    tables[current_table]['columns'].append((name, type, extra))
                # Is it a constraint or something?
                elif line.startswith("PRIMARY KEY"):
                    creation_lines.append(line.rstrip(",").lower())
                    primary_key = line.split("(")[1].split(")")[0].lower()
                elif line.startswith("UNIQUE KEY"):
                    creation_lines.append("UNIQUE (%s)" % line.split("(")[1].split(")")[0].lower())
                elif line.startswith("KEY"):
                    index_lines.append("CREATE INDEX %s on \"%s\" (%s)" % (line.split(" ")[1], current_table, line.split("(")[1].split(")")[0].lower()))
                # Is it the end of the table?
                elif line == ");" or line == ")":
                    output.write("CREATE TABLE \"%s\" (\n" % current_table)
                    for i, line in enumerate(creation_lines):
                        output.write("    %s%s\n" % (line, "," if i != (len(creation_lines) - 1) else ""))
                    if primary_key is not None:
                        output.write(') distributed by (%s);\n\n' % primary_key)
                    else:
                        output.write(') distributed by ();\n\n')
                    current_table = None
                    primary_key = None
                # ???
                else:
                    print "\n ! Unknown line inside table creation: %s" % line
    
        # Finish file
        output.write("\n-- Post-data save --\n")
        output.write("\n-- Add Comment --\n")
    
        for line in comment_line:
            output.write(u"%s;\n" % line)
    
        output.write("COMMIT;\n\n")
    
        # Write index out
        # output.write("START TRANSACTION;\n")
        # output.write("\n-- Index --\n")
        # for line in index_lines:
        #     output.write("%s;\n" % line)
        #
        # # Finish file
        # output.write("\n")
        # output.write("COMMIT;\n")
        print ""
    
    
    if __name__ == "__main__":
        parse(sys.argv[1], sys.argv[2])

参考:[https://github.com/wuchase/mysql-postgresql-converter][https_github.com_wuchase_mysql-postgresql-converter]

[https_github.com_wuchase_mysql-postgresql-converter]: https://github.com/wuchase/mysql-postgresql-converter