Functions/Merge-Migration.ps1
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function Merge-Migration { <# .SYNOPSIS Creates a cumulative set of operations from migration scripts. .DESCRIPTION The `Merge-Migration` functions creates a cumulative set of migrations from migration scripts. If there are multiple operations across one or more migration scripts that touch the same database object, those changes are combined into one operation. For example, if you create a table in one migration, add a column in another migrations, then remove a column in a third migration, this function will output an operation that represents the final state for the object: a create table operation that includes the added column and doesn't include the removed column. In environments where tables are replicated, it is more efficient to modify objects once and have that change replicated once, than to have the same object modified multiple times and replicated multiple times. This function returns `Rivet.Migration` objects. Each object will have zero or more operations in its `PushOperations` property. If there are zero operations, it means the original operation was consolidated into another migration. Each operation has `Source` member on it, which is a list of all the migrations that contributed to that operation. .OUTPUTS Rivet.Migration .EXAMPLE Get-Migration | Merge-Migration Demonstrates how to run `Merge-Migration`. It is always used in conjunction with `Get-Migration`. #> [CmdletBinding()] [OutputType([Rivet.Migration])] param( [Parameter(ValueFromPipeline=$true)] [Rivet.Migration[]] # The path to the rivet.json file to use. By default, it will look in the current directory. $Migration ) begin { Set-StrictMode -Version 'Latest' function Get-ColumnIndex { param( [Parameter(Mandatory=$true,ValueFromPipeline=$true)] [string] # The column to check for. $Name, [Parameter(Mandatory=$true)] [Collections.Generic.List[Rivet.Column]] [AllowEmptyCollection()] # The column collection to modify $List ) $columnIdx = $null for( $idx = 0; $idx -lt $List.Count; ++$idx ) { if( $List[$idx].Name -eq $Name ) { return $idx } } } filter Add-Column { param( [Parameter(Mandatory=$true,ValueFromPipeline=$true)] [Rivet.Column] # The column to check for. $Column, [Parameter(Mandatory=$true)] [Collections.Generic.List[Rivet.Column]] [AllowEmptyCollection()] # The column collection to modify $List, [Switch] # Replace only, don't add. $ReplaceOnly ) $columnIdx = Get-ColumnIndex -Name $Column.Name -List $List if( $columnIdx -eq $null ) { if( -not $ReplaceOnly ) { [void] $List.Add( $column ) return $true } } else { $null = $List.RemoveAt( $columnIdx ) $List.Insert( $columnIdx, $column ) return $true } return $false } filter Remove-Column { param( [Parameter(Mandatory=$true,ValueFromPipeline=$true)] [string] # The column to check for. $Name, [Parameter(Mandatory=$true)] [Collections.Generic.List[Rivet.Column]] [AllowEmptyCollection()] # The column collection to modify $List ) $columnIdx = Get-ColumnIndex -Name $Name -List $List if( $columnIdx -ne $null ) { [void] $List.RemoveAt( $columnIdx ) return $true } return $false } $databaseName = $null $migrations = New-Object 'Collections.Generic.List[Rivet.Migration]' [Collections.Generic.Hashset[string]]$preExistingObjects = $null [Collections.Generic.HashSet[string]]$newTables = $null [Collections.ArrayList]$operations = $null function Reset-OperationState { Set-Variable -Name 'newTables' -Scope 1 -Value (New-Object 'Collections.Generic.HashSet[string]') # list of every single operation we encounter across migrations Set-Variable -Name 'operations' -Scope 1 -Value (New-Object 'Collections.ArrayList') Set-Variable -Name 'preExistingObjects' -Scope 1 -Value (New-Object 'Collections.Generic.Hashset[string]') } } process { #$DebugPreference = 'Continue' foreach( $currentMigration in $Migration ) { if( $databaseName -ne $Migration.Database ) { Reset-OperationState $databaseName = $Migration.Database } function Register-Source { [CmdletBinding()] param( [Rivet.Operation] $Operation ) Set-StrictMode -Version 'Latest' #$DebugPreference = 'SilentlyContinue' Write-Debug -Message ('Current Migration Name: <{0}>' -f $migrationName) Write-Debug -Message ('Operation Type: <{0}>' -f $Operation.GetType().FullName) Write-Debug -Message ('Start Source Count: <{0}>' -f $Operation.Source.Count) foreach( $source in $Operation.Source ) { Write-Debug -Message ('Source Migration Name: <{0}>' -f $source.FullName) if( $source.FullName -eq $migrationName ) { return } } $Operation.Source.Add( $currentMigration ) Write-Debug -Message ('End Source Count: <{0}>' -f $Operation.Source.Count) } $migrationName = '{0}_{1}' -f $currentMigration.ID,$currentMigration.Name Write-Debug -Message ('{0}' -f $currentMigration.Path) $migrations.Add( $currentMigration ) $pushOpIdx = 0 for( $pushOpIdx = 0; $pushOpIdx -lt $currentMigration.PushOperations.Count; ++$pushOpIdx ) { function Remove-CurrentOperation { if( $pushOpIdx -ge $currentMigration.PushOperations.Count ) { Write-Debug 'WTF?!' } $operation = $currentMigration.PushOperations[$pushOpIdx] $currentMigration.PushOperations.RemoveAt( $pushOpIdx ) Set-Variable -Name 'pushOpIdx' -Scope 1 -Value ($pushOpIdx - 1) Remove-Operation $operation } function Remove-Operation { param( $Operation ) for( $idx = $operations.Count - 1; $idx -ge 0; --$idx ) { if( $operations[$idx] -eq $Operation ) { $operations.RemoveAt( $idx ) return } } } function Remove-OperationFromMigration { param( [Rivet.Operation] $Operation ) $opIdx = -1 $originalMigration = $Operation.Source[0] $ops = $originalMigration.PushOperations for( $idx = 0; $idx -lt $ops.Count; ++$idx ) { if( $ops[$idx] -eq $Operation ) { $opIdx = $idx } } if( $opIdx -gt -1 ) { $ops.RemoveAt( $opIdx ) if( $originalMigration -eq $currentMigration ) { Set-Variable -Name 'pushOpIdx' -Scope 1 -Value ($pushOpIdx - 1) } Remove-Operation $Operation } } $op = $currentMigration.PushOperations[$pushOpIdx] $previousObjectOps = $operations | Where-Object { $_ } | Where-Object { Get-Member -InputObject $_ -Name 'ObjectName' } | Where-Object { Get-Member -InputObject $op -Name 'ObjectName' } | Where-Object { $_.ObjectName -eq $op.ObjectName } [void]$operations.Add( $op ) $source = New-Object -TypeName 'Collections.Generic.List[Rivet.Migration]' $op | Add-Member -Name 'Source' -MemberType NoteProperty -Value $source Register-Source $op if( $op -is [Rivet.Operations.AddTableOperation] ) { [void]$newTables.Add( $op.ObjectName ) continue } if( $op -is [Rivet.Operations.RenameColumnOperation] ) { $tableName = '{0}.{1}' -f $op.SchemaName,$op.TableName for( $idx = 0 ; $idx -lt $operations.Count; ++$idx ) { $tableOp = $operations[$idx] if( $tableOp -isnot [Rivet.Operations.AddTableOperation] ) { continue } if( $tableOp.ObjectName -ne $tableName ) { continue } $originalColumn = $tableOp.Columns | Where-Object { $_.Name -eq $op.Name } if( $originalColumn ) { $originalColumn.Name = $op.NewName Register-Source $tableOp Remove-CurrentOperation continue } } continue } if( $op -is [Rivet.Operations.RenameOperation] ) { $objectName = '{0}.{1}' -f $op.SchemaName,$op.Name for( $idx = 0 ; $idx -lt $operations.Count; ++$idx ) { $existingOp = $operations[$idx] if( $existingOp -isnot [Rivet.Operations.AddTableOperation] ) { continue } if( $existingOp.ObjectName -ne $objectName ) { continue } $existingOp.Name = $op.NewName Register-Source $existingOp Remove-CurrentOperation continue } } if( $op -isnot [Rivet.Operations.ObjectOperation] ) { continue } $opTypeName = $op.GetType().Name $isRemoveOperation = $opTypeName -like 'Remove*' # If the first action against this object is a removal if( $isRemoveOperation -and -not $previousObjectOps -and $op -is [Rivet.Operations.ObjectOperation] ) { [void]$preexistingObjects.Add( $op.ObjectName ) } foreach( $existingOp in $previousObjectOps ) { if( $existingOp -eq $op ) { continue } Register-Source $existingOp if( $isRemoveOperation ) { for( $idx = 0; $idx -lt $operations.Count; ++$idx ) { if( $operations[$idx] -eq $existingOp ) { $operations[$idx] = $null } } $originalMigration = $existingOp.Source[0] # Remove the original add operation from its migration Remove-OperationFromMigration -Operation $existingOp if( $op -is [Rivet.Operations.RemoveTableOperation] ) { for( $idx = $operations.Count - 1; $idx -ge 0 ; --$idx ) { $tableOp = $operations[$idx] if( $tableOp -and ($tableOp | Get-Member 'ObjectName') ) { Write-Debug $tableOp.ObjectName } if( $tableOp -isnot [Rivet.Operations.TableObjectOperation] ) { continue } Write-Debug ' is a table object operation' $tableOpTableName = '{0}.{1}' -f $tableOp.SchemaName,$tableOp.TableName if( $op.ObjectName -eq $tableOpTableName ) { Remove-OperationFromMigration -Operation $tableOp } } } if( $existingOp -and -not $preexistingObjects.Contains($existingOp.ObjectName) ) { Remove-CurrentOperation } continue } elseif( $opTypeName -eq 'UpdateTableOperation' ) { if( $existingOp -is [Rivet.Operations.AddTableOperation] ) { $op.AddColumns | Add-Column -List $existingOp.Columns | Out-Null $op.UpdateColumns | Add-Column -List $existingOp.Columns | Out-Null $op.RemoveColumns | Remove-Column -List $existingOp.Columns | Out-Null Remove-CurrentOperation } elseif( $existingOp -is [Rivet.Operations.UpdateTableOperation] ) { if( $op.AddColumns -and $op.AddColumns.Count -gt 0 ) { # If adding a column that was previously removed, remove the removal $op.AddColumns | Select-Object -ExpandProperty 'Name' | ForEach-Object { $columnName = $_ $columnIdx = -1 for( $idx = 0; $idx -lt $existingOp.RemoveColumns.Count; ++$idx ) { if( $existingOp.RemoveColumns[$idx] -eq $columnName ) { $columnIdx = $idx break } } if( $columnIdx -ge 0 ) { $existingOp.RemoveColumns.RemoveAt( $columnIdx ) } } # Add new columns to the original operation for( $colIdx = 0; $colIdx -lt $op.AddColumns.Count; ++$colIdx ) { Add-Column -Column $op.AddColumns[$colIdx] -List $existingOp.AddColumns | Out-Null $op.AddColumns.RemoveAt( $colIdx-- ) } } # Replace existing column definitions for( $colIdx = 0; $colIdx -lt $op.UpdateColumns.Count; ++$colIdx ) { $column = $op.UpdateColumns[$colIdx] $moved = Add-Column -Column $column -List $existingOp.AddColumns -ReplaceOnly $moved = $moved -or (Add-Column -Column $column -List $existingOp.UpdateColumns) if( $moved ) { $op.UpdateColumns.RemoveAt( $colIdx-- ) } } # Remove columns for( $colIdx = 0; $colIdx -lt $op.RemoveColumns.Count; ++$colIdx ) { $columnName = $op.RemoveColumns[$colIdx] # Remove a column we previously added $removedFromAddedColumns = Remove-Column -List $existingOp.AddColumns -Name $columnName $removedFromUpdatedColumns = Remove-Column -List $existingOp.UpdateColumns -Name $columnName $op.RemoveColumns.RemoveAt( $colIdx-- ) if( -not ($removedFromAddedColumns -or $removedFromUpdatedColumns) ) { [void] $existingOp.RemoveColumns.Add( $columnName ) } } if( -not $op.ToQuery() ) { Remove-CurrentOperation } if( -not $existingOp.ToQuery() ) { Remove-OperationFromMigration -Operation $existingOp } } else { Write-Error ('Unhandled operation of type ''{0}''.' -f $existingOp.GetType()) } continue } } } } } end { $migrations.ToArray() } } |