Commands/ConvertTo-SqlMigrationPlan.ps1
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<# Copyright 2021 Jeffrey Sharp Permission to use, copy, modify, and distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. #> function ConvertTo-SqlMigrationPlan { <# .SYNOPSIS Converts a set of migrations resolved by Resolve-SqlMigrations into a plan to apply the migrations to a target database. #> param ( # Set of migrations to convert. [Parameter(Mandatory)] [System.Collections.Specialized.OrderedDictionary] $Migrations, # Path of directory in which to save the plan scripts. [Parameter(Mandatory)] [string] $Path ) <# Case 1: No dependencies ======================= These migrations: 1 | Pre Core Post 2 | Pre Core Post 3 | Pre Core Post 4 | Pre Core Post 5 | Pre Core Post Yield this order operations: | Pre | Core | Post | -------------------------------------------------------------------------------- 1 | Pre | Core | Post | 2 | Pre | Core | Post | 3 | Pre | Core | Post | 4 | Pre | Core | Post | 5 | Pre | Core | Post | Time--> Case 2: One dependency ====================== These migrations: 1 | Pre Core Post 2 | Pre Core Post<--, 3 | Pre Core Post | 4 | Pre Core Post---' Migration4 depends on Migration2 5 | Pre Core Post Yield this order operations: | Pre | Core | Post | ------------------------------------------------------------------------------- 1 | Pre | Core Post | | 2 | Pre | Core ^^^^ Post | | 3 | Pre | Core ^^^^ | Post | 4 | | Pre Core | Post | 5 | | ^^^ Pre Core | Post | Time--> ^^^ This was deemed too optimistic: | Pre | Core | Post | -------------------------------------------------------------------------------- 1 | Pre | Core | Post | 2 | Pre | Core Post | | 3 | Pre | ^^^^ Core | Post | 4 | | Pre Core | Post | 5 | Pre | ^^^ Core | Post | Time--> This was deemed too pessimistic: | Pre | Core | Post | ------------------------------------------------------------------------------- 1 | Pre | Core Post | | 2 | | Pre Core Post | | 3 | | Pre Core Post | | 4 | | Pre Core Post | | 5 | | Pre Core | Post | Time--> Rules ===== Pre = Pres from migrations before any that depend on an unfinished migration. Core = Everything else. Post = Posts from migrations after any that are depended upon by an unfinished migration. Migration N's Pres are guaranteed to run after all of Migration N-1's Pres. Migration N's Cores are guaranteed to run after all of Migration N-1's Cores. Migration N's Posts are guaranteed to run after all of Migration N-1's Posts. Only the greatest dependency name for each migration matters. #> # Phases $Pre = [PSCustomObject] @{ Number = 1; Name = "Pre"; Count = 0; IsUsed = $false } $Core = [PSCustomObject] @{ Number = 2; Name = "Core"; Count = 0; IsUsed = $false } $Post = [PSCustomObject] @{ Number = 3; Name = "Post"; Count = 0; IsUsed = $false } # Compute ideal ordering, irrespective of dependencies $Tasks = @(foreach ($Phase in $Pre, $Core, $Post) { $Migrations.Values ` | ? { $_.State -lt $Phase.Number } ` | % { $Phase.Count++ [PSCustomObject] @{ Done = $false Phase = $Phase Migration = $_ Depends = $_ ` | % Depends ` | ? { $Migrations[$_].State -lt $Post.Number } ` | ConvertTo-StringHashSet } } }) # Initialize target directory $Path = New-Item $Path -Type Directory -Force | % FullName $Path | Join-Path -ChildPath * | Remove-Item -Recurse # Write Pre phase # Stop after last Pre phase or before any Pre phase that depends on something Optimize-SqlMigrationPlanPhase $Pre $Tasks ` -StopIf { param($Task) $Task.Phase.Name -ne "Pre" -or $Task.Depends.Count } ` | Out-File -LiteralPath (Join-Path $Path 1_Pre.sql) -Encoding utf8 -Force # Output Core phase # Stop after last migration Core phase is visited Optimize-SqlMigrationPlanPhase $Core $Tasks ` -StopIf { param($Task) !$Core.Count } ` -SkipIf { param($Task) $Task.Depends.Count } ` | Out-File -LiteralPath (Join-Path $Path 2_Core.sql) -Encoding utf8 -Force # Output Post phase # Stop when all phases are visited Optimize-SqlMigrationPlanPhase $Post $Tasks ` | Out-File -LiteralPath (Join-Path $Path 3_Post.sql) -Encoding utf8 -Force [PSCustomObject] @{ Path = $Path RequiresOffline = $Core.IsUsed } } function Optimize-SqlMigrationPlanPhase { param ( [Parameter(Mandatory)] [object] $Phase, [Parameter(Mandatory)] [AllowEmptyCollection()] [object[]] $Tasks, [Parameter()] [scriptblock] $StopIf, [Parameter()] [scriptblock] $SkipIf ) Write-Verbose "Computing $($Phase.Name) Phase" $Start = 0 $Count = $Tasks.Length # Make multiple passes through tasks. # Stop when until-condition is met or all tasks are done. while ($Start -lt $Count) { for ($i = $Start; $i -lt $Count; $i++) { $Task = $Tasks[$i] Write-Verbose "Considering $($Task.Migration.Name)[$($Task.Phase.Name)]" # Skip task if done if ($Task.Done) { Write-Verbose "...already visited" if ($i -eq $Start) { $Start++ } continue } # Check if should stop if ($StopIf -and $StopIf.Invoke($Task)) { Write-Verbose "...should stop assembling this phase" return } # Check if should skip further tasks of same phase if ($SkipIf -and $SkipIf.Invoke($Task)) { Write-Verbose "...should skip further tasks from the $($Task.Phase.Name) Phase" for ($j = $i + 1; $j -le $Count; $i = $j++) { if ($Tasks[$j].Phase -ne $Tasks[$i].Phase) { break } } continue } # Output migration Pre phase Write-Verbose "...writing to $($Phase.Name) Phase" Format-SqlMigrationPhase $Task.Migration $Task.Phase # Record task as done $Task.Done = $true $Task.Phase.Count-- # Handle when entire migration is done if ($Task.Phase.Number -eq 3 <# Post #>) { # Remove dependencies on that migration if ($Tasks | ? { $_.Depends.Remove($Task.Migration.Name) }) { # Dependency was actually removed; restart scan from $Start # to catch earlier tasks that can be visited now. break } } # If we revisit, skip earlier tasks if ($i -eq $Start) { $Start++ } } } } function ConvertTo-StringHashSet { [OutputType([System.Collections.Generic.HashSet[string]])] param ( [Parameter(ValueFromPipeline)] [string[]] $Items ) begin { $Comparer = [StringComparer]::OrdinalIgnoreCase $HashSet = New-Object System.Collections.Generic.HashSet[string] $Comparer } process { $Items | % { [void] $HashSet.Add($_) } } end { Write-Output $HashSet -NoEnumerate } } function Format-SqlMigrationPhase { param ( [Parameter(Mandatory)] [object] $Migration, [Parameter(Mandatory)] [object] $Phase ) $Name = $Migration.Name -replace "'", "''" $Sql = $Migration | % "$($Phase.Name)Sql" # If migration has actual code to run in this phase, mark the phase as used. if ($Sql) { $Phase.IsUsed = $true } Write-Output @" GO -- ----------------------------------------------------------------------------- PRINT '*** $Name $($Phase.Name) ***'; GO "@ Write-Output $Sql # Ensure psedo-migrations (_Begin, _End) never get registered if ($Migration.IsPseudo) { return } Write-Output @" GO -- ----------------------------------------------------------------------------- PRINT '+ updt _deploy.Migration ($Name $($Phase.Name) done)'; GO MERGE _deploy.Migration dst USING ( SELECT Name = '$Name', Hash = '$($Migration.Hash)', Date = SYSUTCDATETIME() ) src ON src.Name = dst.Name WHEN MATCHED THEN UPDATE SET dst.Hash = src.Hash, dst.$($Phase.Name)RunDate = src.Date WHEN NOT MATCHED BY TARGET THEN INSERT (Name, Hash, $($Phase.Name)RunDate) VALUES (Name, Hash, Date) ; IF @@ROWCOUNT != 1 THROW 50000, 'Migration registration for $Name failed.', 0; "@ } |