Class: Exwiw::Adapter::MysqlAdapter

Inherits:
Base
  • Object
show all
Includes:
IdentifierQuoting::Mysql, SqlBulkInsert
Defined in:
lib/exwiw/adapter/mysql_adapter.rb

Defined Under Namespace

Classes: StreamingResult

Constant Summary collapse

SPECIAL_CHARACTER_ESCAPES =

Backslash and control-character escapes, matching mysqldump. Escaping newlines keeps every VALUES tuple on a single line, so a value that itself contains a newline cannot break consumers that split the dump into statements on a semicolon-newline boundary.

{
  "\\" => "\\\\",
  "\n" => "\\n",
  "\r" => "\\r",
  "\u0000" => "\\0",
  "\u001A" => "\\Z",
}.freeze

Constants included from SqlBulkInsert

SqlBulkInsert::STREAM_FLUSH_ROWS

Constants included from IdentifierQuoting

IdentifierQuoting::BARE_IDENTIFIER_PATTERN, IdentifierQuoting::MYSQL_RESERVED_WORDS, IdentifierQuoting::POSTGRESQL_RESERVED_WORDS, IdentifierQuoting::SQLITE_RESERVED_WORDS

Instance Attribute Summary

Attributes inherited from Base

#connection_config

Instance Method Summary collapse

Methods included from SqlBulkInsert

#to_bulk_insert, #write_inserts

Methods included from IdentifierQuoting

#force_quote_identifier, #force_quote_table_name, #qualified_name, #quote_identifier, #quote_table_name

Methods inherited from Base

#commented_sql, #default_bulk_insert_chunk_size, #describe_query, #dumpable?, #explain_scope_with_placeholders!, #initialize, #output_extension, #query_comment_text, #schema_output_extension, #sql_query_comment, #supports_bulk_delete?, table_config_class, #to_copy_from_stdin, #validate_as_dump_target!, #write_inserts

Constructor Details

This class inherits a constructor from Exwiw::Adapter::Base

Instance Method Details

#build_query(table, dump_target, table_by_name) ⇒ Object 



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# File 'lib/exwiw/adapter/mysql_adapter.rb', line 57

def build_query(table, dump_target, table_by_name)
  Exwiw::QueryAstBuilder.run(table.name, table_by_name, dump_target, @logger)
end

#compile_ast(query_ast, count_only: false) ⇒ Object

Parameters:

  • count_only (Boolean) (defaults to: false) —

    emit SELECT COUNT(*) instead of the projected columns (used by StreamingResult#size). Safe because exwiw's extraction queries have no DISTINCT/GROUP BY/LIMIT, so the count does not depend on the projection.

Raises:

  • (NotImplementedError) 


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# File 'lib/exwiw/adapter/mysql_adapter.rb', line 231

def compile_ast(query_ast, count_only: false)
  raise NotImplementedError unless query_ast.is_a?(Exwiw::QueryAst::Select)

  # Lift scope id-set clauses (reverse_scope UNION / forward cascade /
  # single referenced_by) out of `WHERE <col> IN (subquery)` and into a
  # JOIN against a materialized derived table. See #compile_scope_join.
  scope_clauses, plain_where_clauses = partition_scope_clauses(query_ast.where_clauses)

  sql = "SELECT "
  sql += if count_only
           "COUNT(*)"
         elsif query_ast.select_all
           # A lifted scope JOIN brings a derived table into FROM, so a bare
           # `*` would also project its column. Qualify to this table's own.
           scope_clauses.any? ? "#{quote_table_name(query_ast.from_table_name)}.*" : "*"
         else
           query_ast.columns.map { |col| compile_column_name(query_ast, col) }.join(', ')
         end
  sql += " FROM #{quote_table_name(query_ast.from_table_name)}"

  query_ast.join_clauses.each do |join|
    sql += " JOIN #{quote_table_name(join.join_table_name)} ON #{qualified_name(join.base_table_name, join.foreign_key)} = #{qualified_name(join.join_table_name, join.primary_key)}"

    join.where_clauses.each do |where|
      compiled_where_condition = compile_where_condition(where, join.join_table_name)
      sql += " AND #{compiled_where_condition}"
    end

    # base_where_clauses is compiled against the joined-from table
    # (base_table_name), e.g. the type-column filter on a polymorphic
    # source table.
    join.base_where_clauses.each do |where|
      compiled_where_condition = compile_where_condition(where, join.base_table_name)
      sql += " AND #{compiled_where_condition}"
    end
  end

  scope_clauses.each_with_index do |where_clause, idx|
    sql += " #{compile_scope_join(query_ast.from_table_name, where_clause, idx)}"
  end

  if plain_where_clauses.any?
    sql += " WHERE "
    sql += plain_where_clauses.map { |where| compile_where_condition(where, query_ast.from_table_name) }.join(' AND ')
  end

  sql
end

#dump_schema(ordered_tables, output_path) ⇒ Object 



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# File 'lib/exwiw/adapter/mysql_adapter.rb', line 83

def dump_schema(ordered_tables, output_path)
  # Full-database schema dump: emit DDL for every table in the database,
  # not just the config-scoped tables. A table absent from the config gets
  # its schema here but no data (empty INSERT), which is the intended
  # result — the restore target then has every relation even when exwiw was
  # configured to extract only a subset. `ordered_tables` no longer selects
  # which tables are emitted; it is kept only for the log line.

  # The mysqldump binary is invoked directly (not via the mysql2/trilogy
  # driver), so point EXWIW_MYSQLDUMP at a specific binary when the one on
  # PATH is incompatible with the server — e.g. a MySQL 9.x client whose
  # mysqldump cannot load `mysql_native_password` ("plugin ... cannot be
  # loaded", exit 2) against a server still using that auth plugin.
  mysqldump_bin = ENV['EXWIW_MYSQLDUMP']
  mysqldump_bin = 'mysqldump' if mysqldump_bin.nil? || mysqldump_bin.empty?

  # MariaDB's mysqldump does not recognise the MySQL-specific
  # --set-gtid-purged flag and exits with code 7.
  gtid_flags = mariadb_mysqldump?(mysqldump_bin) ? [] : ['--set-gtid-purged=OFF']

  cmd = [
    mysqldump_bin,
    "--host=#{@connection_config.host}",
    "--port=#{@connection_config.port}",
    "--user=#{@connection_config.user}",
    '--no-data',
    '--skip-add-drop-table',
    '--skip-comments',
    '--skip-set-charset',
    '--no-tablespaces', # skip tablespace query that requires PROCESS privilege (unavailable on managed MySQL like RDS)
    *gtid_flags,
    '--compact',
    @connection_config.database_name,
  ]
  env = { 'MYSQL_PWD' => @connection_config.password.to_s }

  @logger.debug("  Running #{mysqldump_bin} for the whole database (#{@connection_config.database_name})...")
  stdout, stderr, status =
    begin
      Open3.capture3(env, *cmd)
    rescue Errno::ENOENT
      raise "Failed to run `#{mysqldump_bin}`. Ensure the mysql client is installed and on PATH, " \
            "or set EXWIW_MYSQLDUMP to a mysqldump binary."
    end
  unless status.success?
    if stderr.include?('command not found') || stderr.empty?
      raise "Failed to run `#{mysqldump_bin}`. Ensure the mysql client is installed and on PATH, " \
            "or set EXWIW_MYSQLDUMP to a mysqldump binary. stderr: #{stderr}"
    end
    raise "mysqldump failed (exit #{status.exitstatus}): #{stderr}"
  end

  idempotent = DdlPostprocessor.add_if_not_exists_to_create_table(stdout)

  File.open(output_path, 'w') do |file|
    file.puts("-- Auto-generated by exwiw via mysqldump. Idempotent CREATE TABLE statements for mysql.")
    file.puts("SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0;")
    file.puts
    file.puts(idempotent)
    file.puts("SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS;")
  end
  @logger.info("  Wrote full-database schema to #{output_path} (#{ordered_tables.size} table(s) in scope for data).")
end

#execute(query_ast) ⇒ Object 



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# File 'lib/exwiw/adapter/mysql_adapter.rb', line 61

def execute(query_ast)
  data_sql = commented_sql(query_ast)
  # Count via the same FROM/JOIN/WHERE (projection replaced by COUNT(*)) so
  # the Runner can skip empty tables and log the row count without draining
  # the stream. See StreamingResult for why this is not a subquery wrap.
  count_sql = "#{sql_query_comment(query_ast)} #{compile_ast(query_ast, count_only: true)}"

  @logger.debug("  Executing SQL (streaming): \n#{data_sql}")
  StreamingResult.new(client: connection, data_sql: data_sql, count_sql: count_sql)
end

#explain(query_ast, verbosity: nil) ⇒ Object 



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# File 'lib/exwiw/adapter/mysql_adapter.rb', line 72

def explain(query_ast, verbosity: nil)
  sql = commented_sql(query_ast)

  @logger.debug("  Executing EXPLAIN: \n#{sql}")
  result = connection.query("EXPLAIN #{sql}")
  result.rows.each_with_index.flat_map do |row, i|
    ["*************************** #{i + 1}. row ***************************"] +
      result.fields.zip(row).map { |k, v| "#{k}: #{v}" }
  end.join("\n")
end

#post_insert_sql(_table) ⇒ Object 



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# File 'lib/exwiw/adapter/mysql_adapter.rb', line 151

def post_insert_sql(_table)
  "SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS;"
end

#pre_insert_sql(_table) ⇒ Object 



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# File 'lib/exwiw/adapter/mysql_adapter.rb', line 147

def pre_insert_sql(_table)
  "SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0;"
end

#to_bulk_delete(select_query_ast, table) ⇒ Object

Raises:

  • (NotImplementedError) 


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# File 'lib/exwiw/adapter/mysql_adapter.rb', line 169

def to_bulk_delete(select_query_ast, table)
  raise NotImplementedError unless select_query_ast.is_a?(Exwiw::QueryAst::Select)

  sql = "DELETE FROM #{quote_table_name(select_query_ast.from_table_name)}"

  if select_query_ast.join_clauses.empty?
    # Ignore filter option, because bulk delete is for cleaning before import,
    # so it should delete all records to avoid foreign key violation & data consistancy.
    compiled_where_conditions = select_query_ast.
      where_clauses.
      select { |where| where.is_a?(Exwiw::QueryAst::WhereClause) }.
      map do |where|
      compile_where_condition(where, select_query_ast.from_table_name)
    end

    if compiled_where_conditions.size > 0
      sql += "\nWHERE "
      sql += compiled_where_conditions.join(' AND ')
    end
    sql += ";"

    return sql
  end

  subquery_ast = Exwiw::QueryAst::Select.new
  first_join = select_query_ast.join_clauses.first.clone

  subquery_ast.from(first_join.join_table_name)
  primay_key_col = table.columns.find { |col| col.name == table.primary_key }
  subquery_ast.select([primay_key_col])
  select_query_ast.join_clauses[1..].each do |join|
    subquery_ast.join(join)
  end
  first_join.where_clauses.each do |where|
    # Ignore filter option, because bulk delete is for cleaning before import,
    # so it should delete all records to avoid foreign key violation & data consistancy.
    subquery_ast.where(where) if where.is_a?(Exwiw::QueryAst::WhereClause)
  end

  foreign_key = first_join.foreign_key
  subquery_sql = compile_ast(subquery_ast)
  sql += "\nWHERE #{qualified_name(select_query_ast.from_table_name, foreign_key)} IN (#{subquery_sql})"

  # first_join.base_where_clauses holds conditions on the outer
  # delete-target table (from_table_name), such as a polymorphic type
  # column. They are not part of the subquery, so add them to the outer
  # WHERE. This prevents deleting rows that belong to a different
  # polymorphic type.
  first_join.base_where_clauses.each do |where|
    next unless where.is_a?(Exwiw::QueryAst::WhereClause)

    sql += " AND #{compile_where_condition(where, select_query_ast.from_table_name)}"
  end
  sql += ";"

  sql
end