Sql.Database.Logical.Versioned

Unit
Source
Symbols

Symbol	Description
ESqlVersionedDatabase
ESqlVersioningIncompatibility	Indicates an SQL statement that should be augmented by the `TVersionedSqlDatabase`, but cannot be.
TSqlVersioningTransaction	Represents a single running transaction in the versioned database. Created by the `TVersionedSqlDatabase` when a new transaction is started.
TSqlVersioningUpdateOperation
TVersionedSqlDatabase	Decorates a `TSqlDatabase` to add versioning functionality
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///////////////////////////////////////////////////////////////////////////
//                                                                       //
//  Copyright (c) 2015 by Charta Software B.V.                           //
//  All rights reserved                                                  //
//                                                                       //
//  Version:  1.7.0.83525                                                //
//  Web site: https://pascal.chartasoftware.com/                         //
//                                                                       //
//  This code and information are provided "as is" without warranty of   //
//  any kind. Dissemination of this information or reproduction of       //
//  this material is strictly forbidden unless prior written permission  //
//  is obtained from Charta Software B.V..                               //
//                                                                       //
///////////////////////////////////////////////////////////////////////////

unit Sql.Database.Logical.Versioned;

interface

uses
  Boolean,
  Collection.List,
  Exception,
  Integer,
  Sql.Database,
  Sql.Database.Logical.Annotating,
  Sql.Database.Logical.UpdateOperation,
  Sql.Expression,
  Sql.Result,
  Sql.Statement,
  Sql.Statement.DataDefinition.Table.Alter,
  Sql.Statement.DataDefinition.Table.Create,
  Sql.Statement.DataManipulation,
  Sql.Table,
  Sql.Table.Column,
  Sql.Transaction,
  Sql.Transaction.Log,
  Text;

type
  TSqlVersioningTransaction = class(TObject)
  protected
    FId:  TInteger;
    FLog: TSqlTransactionLog;

  public
    constructor Create(const Id: TInteger; Log: TSqlTransactionLog); virtual;

    property    Id: TInteger read FId;
    property    Log: TSqlTransactionLog read FLog;
  end;

  ESqlVersionedDatabase = class(EException);
  ESqlVersioningIncompatibility = class(ESqlVersionedDatabase);

  TSqlVersioningUpdateOperation = class(TLogicalSqlUpdateOperation)
  private
    TransactionId: TInteger;

  protected
    function    IsManagedColumn(Column: TSqlTableColumn): TBoolean; override;

  public
    constructor Create(Database: TSqlDatabase; const TemporaryIdentifier: TText; Table: TSqlTable; Columns: TList<TSqlTableColumn>; const TransactionId: TInteger); reintroduce; virtual;

    function    CreatePresentRestriction(): TSqlExpression; override;

    procedure   AddManagingColumns(InsertSelect: TSqlInsertSelect); override;
    procedure   ValidateManagedColumns(); override;
  end;

  TVersionedSqlDatabase = class(TAnnotatingSqlDatabase)
  protected
    VersioningTransaction: TSqlVersioningTransaction;
    Transaction:           TSqlTransaction;

    procedure   StartUpdateOperation(Table: TSqlTable); override;
    procedure   EndUpdateOperation(); override;

    procedure   AddDeleteRestrictions(Delete: TSqlDelete; Table: TSqlTable); override;
    procedure   AddDeleteAssignments(Update: TSqlUpdate; Table: TSqlTable); override;

    procedure   AddManagingRestrictions(Expression: TSqlExpression); override;
    procedure   UpdateManagingColumns(UpdateOperation: TLogicalSqlUpdateOperation); override;

    function    IsManaged(Table: TSqlTable): TBoolean; overload; override;
    function    IsManaged(Table: TSqlTable; Column: TSqlTableColumn): TBoolean; overload; override;

    function    CreateUpdateOperation(Table: TSqlTable; Columns: TList<TSqlTableColumn>): TLogicalSqlUpdateOperation; override;

    procedure   HandleAlterTable(AlterTable: TSqlAlterTable);
    procedure   HandleCreateTable(CreateTable: TSqlCreateTable);

  public
    function    Query(Statement: TSqlStatement; ResultMethod: TSqlQueryResultMethod = sqrmStoreResult): TSqlResult; override;

    function    StartTransaction(): TSqlTransaction; override;
    procedure   EndTransaction(Transaction: TSqlTransaction); override;
  end;

implementation

uses
  Object_.List,
  Sql,
  Sql.Comparison,
  Sql.Database.Logical.Versioned.RewriteRule,
  Sql.Exception,
  Sql.Literal,
  Sql.Operator_.Binary,
  Sql.Operator_.Unary,
  Sql.Rewriter,
  Sql.Rewriter.Rule,
  Sql.Statement.ResultSet,
  Sql.Statement.ResultSet.Select,
  Sql.Table.Column.Reference,
  Sql.Table.Index,
  Sql.Table.Index.Column;

{ TSqlVersioningTransaction }

constructor TSqlVersioningTransaction.Create(const Id: TInteger; Log: TSqlTransactionLog);
begin
  inherited Create();

  FId  := Id;
  FLog := Log;
end;

{ TVersionedSqlDatabase }

function TVersionedSqlDatabase.StartTransaction(): TSqlTransaction;
begin
  Transaction := inherited StartTransaction();
  Result      := Transaction;
end;

procedure TVersionedSqlDatabase.StartUpdateOperation(Table: TSqlTable);
var
  Log: TSqlTransactionLog;
begin
  if Transaction <> nil then
  begin
    Log := Table.Lifetime.Log;

    if VersioningTransaction = nil then
    begin
      // TODO: Currently we store only one VersioningTransaction, however, more than one Log may be in effect
      VersioningTransaction := TSqlVersioningTransaction.Create(Log.Log(Database, Transaction), Log);
    end
    else if VersioningTransaction.Log <> Log then
      raise ESqlVersioningIncompatibility.Create('Mixing different transaction logs in one transaction');
  end
  else
    raise ESqlVersionedDatabase.Create('Transaction required');
end;

procedure TVersionedSqlDatabase.UpdateManagingColumns(UpdateOperation: TLogicalSqlUpdateOperation);
begin
  Database.Query(
    Update(
      [ UpdateOperation.Table, UpdateOperation.TemporaryTable ],
      [ Assign(UpdateOperation.Table.Lifetime.RemoveTransactionId, Null) ],
      [
        UpdateOperation.CreateRowEquals(),
        UpdateOperation.Table.Lifetime.RemoveTransactionId = VersioningTransaction.Id
      ]
    )
  );
end;

procedure TVersionedSqlDatabase.EndTransaction(Transaction: TSqlTransaction);
begin
  inherited EndTransaction(Transaction);

  Self.Transaction := nil;

  VersioningTransaction.Free();
  VersioningTransaction := nil;
end;

procedure TVersionedSqlDatabase.AddDeleteAssignments(Update: TSqlUpdate; Table: TSqlTable);
begin
  Update.Assignments.Add(Assign(Table.Lifetime.RemoveTransactionId, VersioningTransaction.Id));
end;

procedure TVersionedSqlDatabase.AddDeleteRestrictions(Delete: TSqlDelete; Table: TSqlTable);
begin
  Delete.Restrictions.Add(Equal(Table.Lifetime.AddTransactionId, VersioningTransaction.Id));
end;

procedure TVersionedSqlDatabase.AddManagingRestrictions(Expression: TSqlExpression);
var
  RewriteRule: TSqlRewriteRule;
  Rewriter:    TSqlRewriter;
begin
  RewriteRule := TVersioningSqlRewriteRule.Create();

  Rewriter := TSqlRewriter.Create(RewriteRule);
  Rewriter.DecorateExpression(Expression);
  Rewriter.Free();

  RewriteRule.Free();
end;

procedure TVersionedSqlDatabase.EndUpdateOperation();
begin
end;

procedure TVersionedSqlDatabase.HandleAlterTable(AlterTable: TSqlAlterTable);
var
  WorkingCopy:   TSqlAlterTable;
  Specification: TSqlExpression;
  AddKey:        TSqlAddKey;
  OriginalKey:   TSqlTableKey;
  ExtendedKey:   TSqlTableKey;
  TemporaryKeys: TList<TSqlTableKey>;
  Column:        TSqlTableIndexColumn;
begin
  if IsManaged(AlterTable.Table) then
  begin
    WorkingCopy   := AlterTable.CopyAlterTable();
    TemporaryKeys := TObjectList<TSqlTableKey>.Create();

    for Specification in WorkingCopy.Specifications do
    begin
      if Specification is TSqlAddKey then
      begin
        AddKey      := Specification as TSqlAddKey;
        OriginalKey := AddKey.Key;

        if (OriginalKey is TSqlPrimaryKey) or (OriginalKey is TSqlUniqueKey) then
        begin
          if OriginalKey is TSqlPrimaryKey then
            ExtendedKey := TSqlPrimaryKey.Create([])
          else
            ExtendedKey := TSqlUniqueKey.Create((OriginalKey as TSqlUniqueKey).Name, []);

          AddKey.Key := ExtendedKey;

          for Column in OriginalKey.Columns do
            ExtendedKey.Columns.Add(Column);

          ExtendedKey.Columns.Add(AlterTable.Table.Lifetime.AddTransactionId);
          TemporaryKeys.Add(ExtendedKey);
        end;
      end;
    end;

    Database.Query(WorkingCopy);
    TemporaryKeys.Free();
  end
  else
    Database.Query(AlterTable);
end;

procedure TVersionedSqlDatabase.HandleCreateTable(CreateTable: TSqlCreateTable);
var
  WorkingCopy: TSqlCreateTable;
  Expression:  TSqlExpression;
  Key:         TSqlTableKey;
  CreateKey:   TSqlCreateKey;
  CreatedKey:  TSqlTableKey;
  CreatedKeys: TList<TSqlTableKey>;
  Column:      TSqlTableIndexColumn;
begin
  if IsManaged(CreateTable.Table) then
  begin
    CreatedKeys := TObjectList<TSqlTableKey>.Create();
    WorkingCopy := CreateTable.CopyCreateTable();

    for Expression in WorkingCopy.Specifications do
    begin
      if Expression is TSqlCreateKey then
      begin
        CreateKey := Expression as TSqlCreateKey;
        Key       := CreateKey.Key;

        if (Key is TSqlPrimaryKey) or (Key is TSqlUniqueKey) then
        begin
          if Key is TSqlPrimaryKey then
            CreatedKey := TSqlPrimaryKey.Create([])
          else
            CreatedKey := TSqlUniqueKey.Create((Key as TSqlUniqueKey).Name, []);

          CreateKey.Key := CreatedKey;

          for Column in Key.Columns do
            CreatedKey.Columns.Add(Column);

          CreatedKey.Columns.Add(CreateTable.Table.Lifetime.AddTransactionId);
          CreatedKeys.Add(CreatedKey);
        end;
      end;
    end;

    Database.Query(WorkingCopy);
    CreatedKeys.Free();
  end
  else
    Database.Query(CreateTable);
end;

function TVersionedSqlDatabase.Query(Statement: TSqlStatement; ResultMethod: TSqlQueryResultMethod): TSqlResult;
begin
  Result         := nil;
  UseOwnInsertId := False;

  Statement.AddReference();

  try
    if Statement is TSqlInsertValues then
      HandleInsertValues(Statement as TSqlInsertValues, TSqlAnnotatingInsertType.Insert)
    else if Statement is TSqlInsertSelect then
      HandleInsertSelect(Statement as TSqlInsertSelect, TSqlAnnotatingInsertType.Insert)
    else if Statement is TSqlReplaceValues then
      HandleInsertValues(Statement as TSqlReplaceValues, TSqlAnnotatingInsertType.Replace)
    else if Statement is TSqlResultSetStatement then
      Result := HandleResultSetStatement(Statement as TSqlResultSetStatement, ResultMethod)
    else if Statement is TSqlDelete then
      HandleDelete(Statement as TSqlDelete)
    else if Statement is TSqlUpdate then
      HandleUpdate(Statement as TSqlUpdate)
    else if Statement is TSqlCreateTable then
      HandleCreateTable(Statement as TSqlCreateTable)
    else if Statement is TSqlAlterTable then
      HandleAlterTable(Statement as TSqlAlterTable)
    else
      Result := Database.Query(Statement, ResultMethod);
  finally
    Statement.ReleaseReference();
  end;
end;

function TVersionedSqlDatabase.CreateUpdateOperation(Table: TSqlTable; Columns: TList<TSqlTableColumn>): TLogicalSqlUpdateOperation;
begin
  Result := TSqlVersioningUpdateOperation.Create(Database, 'versioning$temporary', Table, Columns, VersioningTransaction.Id);
end;

function TVersionedSqlDatabase.IsManaged(Table: TSqlTable; Column: TSqlTableColumn): TBoolean;
begin
  Result := (Column = Table.LifeTime.AddTransactionId.Column) or (Column = Table.LifeTime.RemoveTransactionId.Column);
end;

function TVersionedSqlDatabase.IsManaged(Table: TSqlTable): TBoolean;
begin
  Result := Table.Lifetime <> nil;
end;

{ TSqlVersioningUpdateOperation }

procedure TSqlVersioningUpdateOperation.AddManagingColumns(InsertSelect: TSqlInsertSelect);
begin
  InsertSelect.Select.Columns.AddExpression(TSqlLiteralInteger.Create(TransactionId));
  InsertSelect.Columns.Add(Table.LifeTime.AddTransactionId);
end;

constructor TSqlVersioningUpdateOperation.Create(Database: TSqlDatabase; const TemporaryIdentifier: TText; Table: TSqlTable; Columns: TList<TSqlTableColumn>; const TransactionId: TInteger);
begin
  inherited Create(Database, TemporaryIdentifier, Table, Columns);

  Self.TransactionId := TransactionId;
end;

function TSqlVersioningUpdateOperation.CreatePresentRestriction(): TSqlExpression;
begin
  Result := Table.Lifetime.RemoveTransactionId.IsNull;
end;

function TSqlVersioningUpdateOperation.IsManagedColumn(Column: TSqlTableColumn): TBoolean;
begin
  Result := (Column = Table.Lifetime.AddTransactionId.Column) or (Column = Table.Lifetime.RemoveTransactionId.Column);
end;

procedure TSqlVersioningUpdateOperation.ValidateManagedColumns();
var
  Select:          TSqlSelect;
  OrAll:           TSqlOrAll;
  TemporaryColumn: TSqlTableColumn;
begin
  Select := TSqlSelect.Create();
  Select.Columns.AddExpression(TSqlLiteralBoolean.Create(True));
  Select.From.Add(TemporaryTable.ToExpression());

  OrAll := TSqlOrAll.Create();

  if ManagedColumns.Contains(Table.Lifetime.AddTransactionId.Column) then
  begin
    TemporaryColumn := ToTemporary[Table.Lifetime.AddTransactionId.Column];

    OrAll.Expressions.Add(
      not Sql.OrAll([
        TSqlIsNull.Create(TSqlTableColumnReference.Create(TemporaryColumn)),
        TSqlEqual.Create(TSqlTableColumnReference.Create(TemporaryColumn), TSqlLiteralInteger.Create(TransactionId))
      ])
    );
  end;

  if ManagedColumns.Contains(Table.Lifetime.RemoveTransactionId.Column) then
    OrAll.Expressions.Add(TSqlNot.Create(TSqlIsNull.Create(TSqlTableColumnReference.Create(ToTemporary[Table.Lifetime.RemoveTransactionId.Column]))));

  Select.Restrictions.Add(OrAll);

  if Database.Exists(Select) then
    raise ESql.Create('Illegal value specified for version column');
end;

end.