Class: Exwiw::Adapter::SqliteAdapter

Inherits:
Base
  • Object
show all
Includes:
SqlBulkInsert
Defined in:
lib/exwiw/adapter/sqlite_adapter.rb

Defined Under Namespace

Classes: StreamingResult

Constant Summary

Constants included from SqlBulkInsert

Exwiw::Adapter::SqlBulkInsert::STREAM_FLUSH_ROWS

Instance Attribute Summary

Attributes inherited from Base

#connection_config

Instance Method Summary collapse

Methods included from SqlBulkInsert

#to_bulk_insert, #write_inserts

Methods inherited from Base

#commented_sql, #default_bulk_insert_chunk_size, #describe_query, #dumpable?, #initialize, #output_extension, #post_insert_sql, #pre_insert_sql, #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/sqlite_adapter.rb', line 59

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/sqlite_adapter.rb', line 198

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

  sql = "SELECT "
  sql += if count_only
           "COUNT(*)"
         elsif query_ast.select_all
           "*"
         else
           query_ast.columns.map { |col| compile_column_name(query_ast, col) }.join(', ')
         end
  sql += " FROM #{query_ast.from_table_name}"

  query_ast.join_clauses.each do |join|
    sql += " JOIN #{join.join_table_name} ON #{join.base_table_name}.#{join.foreign_key} = #{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

  if query_ast.where_clauses.any?
    sql += " WHERE "
    sql += query_ast.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/sqlite_adapter.rb', line 82

def dump_schema(ordered_tables, output_path)
  @logger.debug("  Reading schema from sqlite_master...")
  target_names = ordered_tables.map(&:name)
  # `sqlite_master` row order preserves table creation order, which is also
  # the dependency order produced by ActiveRecord-style migrations. To respect
  # the caller-provided order, we partition tables / their owned indexes by
  # ordered_tables.
  all = connection.execute(<<~SQL)
    SELECT type, name, tbl_name, sql FROM sqlite_master
    WHERE sql IS NOT NULL AND name NOT LIKE 'sqlite_%'
  SQL

  tables_by_name   = all.select { |type, _, _, _| type == 'table'   }.to_h { |_, name, _, sql| [name, sql] }
  indexes_by_owner = all.select { |type, _, _, _| type == 'index'   }.group_by { |_, _, tbl, _| tbl }
  triggers_by_owner = all.select { |type, _, _, _| type == 'trigger' }.group_by { |_, _, tbl, _| tbl }

  statements = []
  target_names.each do |name|
    table_sql = tables_by_name[name]
    next unless table_sql

    statements << finalize_stmt(DdlPostprocessor.add_if_not_exists_to_create_table(table_sql.strip))
    (indexes_by_owner[name] || []).each do |_, _, _, idx_sql|
      statements << finalize_stmt(DdlPostprocessor.add_if_not_exists_to_create_index(idx_sql.strip))
    end
    (triggers_by_owner[name] || []).each do |_, _, _, trg_sql|
      statements << finalize_stmt(trg_sql.strip)
    end
  end

  File.open(output_path, 'w') do |file|
    file.puts("-- Auto-generated by exwiw. Idempotent CREATE statements for SQLite.")
    file.puts(statements.join("\n"))
  end
  @logger.info("  Wrote #{statements.size} schema statement(s) to #{output_path}.")
end

#execute(query_ast) ⇒ Object 



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# File 'lib/exwiw/adapter/sqlite_adapter.rb', line 63

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 cursor. See StreamingResult for why this is exact.
  count_sql = "#{sql_query_comment(query_ast)} #{compile_ast(query_ast, count_only: true)}"

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

#explain(query_ast) ⇒ Object 



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# File 'lib/exwiw/adapter/sqlite_adapter.rb', line 74

def explain(query_ast)
  sql = commented_sql(query_ast)

  @logger.debug("  Executing EXPLAIN QUERY PLAN: \n#{sql}")
  rows = connection.execute("EXPLAIN QUERY PLAN #{sql}")
  rows.map { |row| row[3] }.join("\n")
end

#to_bulk_delete(select_query_ast, table) ⇒ Object

Raises:

  • (NotImplementedError) 


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# File 'lib/exwiw/adapter/sqlite_adapter.rb', line 136

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

  sql = "DELETE FROM #{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 #{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