SchemaShears — Object-Level Patch Delivery

SchemaShears ships as part of the SchemaSmith distribution — see the Installation guide for how to get the binary on your PATH. Run it from the directory containing your SchemaShears.settings.json:

SchemaShears

To override the configuration file location:

SchemaShears --ConfigFile:path/to/SchemaShears.settings.json

Configuration precedence

SchemaShears reads configuration from multiple sources, merged in this precedence order (highest priority last):

1. Configuration file — SchemaShears.settings.json in the current directory (or the file specified by --ConfigFile).
2. User secrets (debug builds only).
3. Environment variables with the SmithySettings_ prefix.
4. Command-line switches (highest precedence).

For the full list of CLI switches shared by all SchemaSmith tools, see the Configuration Reference.

Configuration file

A complete SchemaShears.settings.json:

{
  "SourcePath": "./MyProduct",
  "ManifestPath": "./patch.manifest",
  "AlwaysIncludePath": "./always-include.txt",
  "OutputPath": "./MyProduct-patch",
  "Zip": false,
  "AllowDrops": ""
}

All keys are optional in the file when the corresponding CLI switch is provided.

The manifest is a plain-text file, one path per line, where each path is relative to the --Source product root:

# Emergency patch for the Orders hotfix
Tables/dbo.Orders.json
Procedures/dbo.ProcessOrder.sql
Procedures/dbo.ValidateOrder.sql
# include the audit function it calls
Functions/dbo.AuditChange.sql

• Lines beginning with # are treated as comments and ignored.
• Blank lines are ignored.
• Paths use forward slashes or backslashes; SchemaShears normalizes them.
• Paths must be relative to the product root (the folder containing Product.json).

Generating a manifest from a commit range

git diff --name-only <before-sha> <after-sha> -- path/to/MyProduct/

Replace path/to/MyProduct/ with the path from your repository root to the product folder. Each line of output is already relative to that root, so you can feed it directly to --Manifest.

For example, to build a patch from all changes between the last release tag and HEAD:

git diff --name-only v2.3.0 HEAD -- MyProduct/ > patch.manifest
SchemaShears --Source:./MyProduct --Manifest:./patch.manifest --Output:./patch

A patch package is a subset of a full product. When SchemaQuench deploys a subset against a target that has the full product installed, it would normally interpret every object absent from the patch as "should be dropped." Drop suppression prevents that: SchemaShears stamps drop-control flags into the emitted patch's Product.json so that absent objects are preserved rather than reconciled away.

Default behavior

By default, SchemaShears suppresses all recognized drop categories. The emitted Product.json carries:

{
  "DropTablesRemovedFromProduct": false,
  "DropColumnsRemovedFromProduct": false,
  "DropUnknownIndexes": false,
  "DropForeignKeysRemovedFromProduct": false,
  "DropCheckConstraintsRemovedFromProduct": false,
  "DropExcludeConstraintsRemovedFromProduct": false,
  "DropStatisticsRemovedFromProduct": false
}

This is the correct posture for a patch: deploy what's in scope, leave everything else alone.

Enforcement

All seven stamped flags are enforced. As of v2.2.0, SchemaQuench's drop-control covers every category SchemaShears suppresses: a table absent from the patch is not dropped, and on the tables the patch does include, columns, foreign keys, check constraints, exclude constraints, and statistics that exist in the target but not in the table JSON are preserved — along with out-of-band indexes (DropUnknownIndexes stays false). See the per-flag sections in the SchemaQuench Reference for exact semantics.

The user promise is: a patch won't drop objects you didn't include — unless you explicitly re-enable a category with --AllowDrops.

Selectively re-enabling drops

Use --AllowDrops (or the AllowDrops settings key) to re-enable specific categories. Pass a comma-separated list of category names — case-insensitive:

SchemaShears --Source:./MyProduct --Manifest:./patch.manifest --Output:./patch --AllowDrops:Columns,Indexes

Valid category names:

Any category not listed in --AllowDrops continues to be suppressed.