first pass: --sample

core/dbt/adapters/base/relation.py

@@ -1,6 +1,7 @@
 from collections.abc import Hashable
 from dataclasses import dataclass, field
 from typing import Optional, TypeVar, Any, Type, Dict, Iterator, Tuple, Set
+import uuid
 
 from dbt.contracts.graph.nodes import SourceDefinition, ManifestNode, ResultNode, ParsedNode
 from dbt.contracts.relation import (
@@ -35,6 +36,7 @@ class BaseRelation(FakeAPIObject, Hashable):
     include_policy: Policy = field(default_factory=lambda: Policy())
     quote_policy: Policy = field(default_factory=lambda: Policy())
     dbt_created: bool = False
+    sample: Optional[int] = None
 
     def _is_exactish_match(self, field: ComponentName, value: str) -> bool:
         if self.dbt_created and self.quote_policy.get_part(field) is False:
@@ -180,7 +182,11 @@ class BaseRelation(FakeAPIObject, Hashable):
 
     def render(self) -> str:
         # if there is nothing set, this will return the empty string.
-        return ".".join(part for _, part in self._render_iterator() if part is not None)
+        rendered_parts = ".".join(part for _, part in self._render_iterator() if part is not None)
+        if self.sample and rendered_parts:
+            alias = f"_dbt_sample_{uuid.uuid4().hex.upper()[:6]}"
+            return f"(select * from {rendered_parts} limit {self.sample}) {alias}"
+        return rendered_parts
 
     def quoted(self, identifier):
         return "{quote_char}{identifier}{quote_char}".format(

core/dbt/cli/main.py

@@ -323,6 +323,7 @@ def docs_serve(ctx, **kwargs):
 @p.profile
 @p.profiles_dir
 @p.project_dir
+@p.sample
 @p.select
 @p.selector
 @p.inline
@@ -551,6 +552,7 @@ def parse(ctx, **kwargs):
 @p.profile
 @p.profiles_dir
 @p.project_dir
+@p.sample
 @p.select
 @p.selector
 @p.state

core/dbt/cli/params.py

@@ -369,6 +369,15 @@ resource_type = click.option(
     default=(),
 )
 
+sample = click.option(
+    "--sample",
+    envvar="DBT_SAMPLE",
+    help="Limit by sample rows when resolving dbt ref and sources.",
+    type=click.INT,
+    default=None,
+)
+
+
 model_decls = ("-m", "--models", "--model")
 select_decls = ("-s", "--select")
 select_attrs = {

core/dbt/context/providers.py

@@ -531,9 +531,13 @@ class RuntimeRefResolver(BaseRefResolver):
     def create_relation(self, target_model: ManifestNode) -> RelationProxy:
         if target_model.is_ephemeral_model:
             self.model.set_cte(target_model.unique_id, None)
-            return self.Relation.create_ephemeral_from_node(self.config, target_model)
+            return self.Relation.create_ephemeral_from_node(
+                self.config, target_model, sample=self.config.args.sample
+            )
         else:
-            return self.Relation.create_from(self.config, target_model)
+            return self.Relation.create_from(
+                self.config, target_model, sample=self.config.args.sample
+            )
 
     def validate(
         self,
@@ -590,7 +594,7 @@ class RuntimeSourceResolver(BaseSourceResolver):
                 target_kind="source",
                 disabled=(isinstance(target_source, Disabled)),
             )
-        return self.Relation.create_from_source(target_source)
+        return self.Relation.create_from_source(target_source, sample=self.config.args.sample)
 
 
 # metric` implementations