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, Union, FrozenSet
+import uuid
 
 from dbt.contracts.graph.nodes import SourceDefinition, ManifestNode, ResultNode, ParsedNode
 from dbt.contracts.relation import (
@@ -36,6 +37,7 @@ 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
 
     # register relation types that can be renamed for the purpose of replacing relations using stages and backups
     # adding a relation type here also requires defining the associated rename macro
@@ -192,7 +194,11 @@ def _render_iterator(self) -> Iterator[Tuple[Optional[ComponentName], Optional[s
 
     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

@@ -342,6 +342,7 @@ def docs_serve(ctx, **kwargs):
 @p.profile
 @p.profiles_dir
 @p.project_dir
+@p.sample
 @p.select
 @p.selector
 @p.inline
@@ -599,6 +600,7 @@ 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

@@ -415,6 +415,14 @@
     hidden=True,
 )
 
+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 @@ def resolve(
     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 @@ def resolve(self, source_name: str, table_name: str):
                 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