diff --git a/backend/open_webui/migrations/versions/c4d7a9e215b8_add_channel_lookup_indexes.py b/backend/open_webui/migrations/versions/c4d7a9e215b8_add_channel_lookup_indexes.py
new file mode 100644
index 0000000000..f6e56b7636
--- /dev/null
+++ b/backend/open_webui/migrations/versions/c4d7a9e215b8_add_channel_lookup_indexes.py
@@ -0,0 +1,90 @@
+"""Add indexes for channel message and reaction lookups and channel message search."""
+
+import logging
+
+import sqlalchemy as sa
+from alembic import op
+
+revision = 'c4d7a9e215b8'
+down_revision = 'e42c8f710a36'
+branch_labels = None
+depends_on = None
+
+INDEXES = [
+    ('ix_message_channel_parent_created', 'message', ['channel_id', 'parent_id', 'created_at']),
+    ('ix_message_parent_id', 'message', ['parent_id']),
+    ('ix_message_reaction_message_id', 'message_reaction', ['message_id']),
+]
+TRIGRAM_INDEX_NAME = 'message_content_trgm_idx'
+FTS_TABLE = 'message_fts'
+FTS_TRIGGERS = ('message_fts_insert', 'message_fts_delete', 'message_fts_update')
+
+
+def upgrade() -> None:
+    for name, table, columns in INDEXES:
+        op.create_index(name, table, columns, if_not_exists=True)
+
+    conn = op.get_bind()
+    if conn.dialect.name == 'postgresql':
+        upgrade_postgresql(conn)
+    elif conn.dialect.name == 'sqlite':
+        upgrade_sqlite(conn)
+
+
+def upgrade_postgresql(conn: sa.Connection) -> None:
+    try:
+        with conn.begin_nested():
+            op.execute('CREATE EXTENSION IF NOT EXISTS pg_trgm')
+            op.create_index(
+                TRIGRAM_INDEX_NAME,
+                'message',
+                ['content'],
+                postgresql_using='gin',
+                postgresql_ops={'content': 'gin_trgm_ops'},
+                if_not_exists=True,
+            )
+    except sa.exc.DBAPIError as exc:
+        if exc.connection_invalidated:
+            raise
+        # Alembic records a skipped attempt too; it will not retry on every startup.
+        logging.getLogger(__name__).warning('Skipped PostgreSQL index %s: %s', TRIGRAM_INDEX_NAME, exc)
+
+
+def upgrade_sqlite(conn: sa.Connection) -> None:
+    try:
+        with conn.begin_nested():
+            op.execute(
+                f'CREATE VIRTUAL TABLE IF NOT EXISTS {FTS_TABLE} USING fts5('
+                "content, content='message', content_rowid='rowid', tokenize='trigram')"
+            )
+            op.execute(
+                f'CREATE TRIGGER IF NOT EXISTS {FTS_TRIGGERS[0]} AFTER INSERT ON message BEGIN '
+                f'INSERT INTO {FTS_TABLE}(rowid, content) VALUES (new.rowid, new.content); END'
+            )
+            op.execute(
+                f'CREATE TRIGGER IF NOT EXISTS {FTS_TRIGGERS[1]} AFTER DELETE ON message BEGIN '
+                f"INSERT INTO {FTS_TABLE}({FTS_TABLE}, rowid, content) VALUES ('delete', old.rowid, old.content); END"
+            )
+            op.execute(
+                f'CREATE TRIGGER IF NOT EXISTS {FTS_TRIGGERS[2]} AFTER UPDATE OF content ON message BEGIN '
+                f"INSERT INTO {FTS_TABLE}({FTS_TABLE}, rowid, content) VALUES ('delete', old.rowid, old.content); "
+                f'INSERT INTO {FTS_TABLE}(rowid, content) VALUES (new.rowid, new.content); END'
+            )
+            op.execute(f"INSERT INTO {FTS_TABLE}({FTS_TABLE}) VALUES ('rebuild')")
+    except sa.exc.DBAPIError as exc:
+        if exc.connection_invalidated:
+            raise
+        logging.getLogger(__name__).warning('Skipped SQLite full-text index %s: %s', FTS_TABLE, exc)
+
+
+def downgrade() -> None:
+    conn = op.get_bind()
+    if conn.dialect.name == 'postgresql':
+        op.drop_index(TRIGRAM_INDEX_NAME, table_name='message', if_exists=True)
+    elif conn.dialect.name == 'sqlite':
+        for trigger in FTS_TRIGGERS:
+            op.execute(f'DROP TRIGGER IF EXISTS {trigger}')
+        op.execute(f'DROP TABLE IF EXISTS {FTS_TABLE}')
+
+    for name, table, _ in INDEXES:
+        op.drop_index(name, table_name=table, if_exists=True)
diff --git a/backend/open_webui/models/messages.py b/backend/open_webui/models/messages.py
index a3f6c45349..0eeaeadb7d 100644
--- a/backend/open_webui/models/messages.py
+++ b/backend/open_webui/models/messages.py
@@ -8,7 +8,22 @@ from open_webui.models.channels import ChannelMember, Channels
 from open_webui.models.tags import Tag, TagModel, Tags
 from open_webui.models.users import User, UserNameResponse, Users
 from pydantic import BaseModel, ConfigDict, computed_field, field_validator
-from sqlalchemy import JSON, BigInteger, Boolean, Column, String, Text, and_, delete, func, or_, select, text, update
+from sqlalchemy import (
+    JSON,
+    BigInteger,
+    Boolean,
+    Column,
+    Index,
+    String,
+    Text,
+    and_,
+    delete,
+    func,
+    or_,
+    select,
+    text,
+    update,
+)
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.sql import exists
 
@@ -17,6 +32,7 @@ from sqlalchemy.sql import exists
 
 class MessageReaction(Base):
     __tablename__ = 'message_reaction'
+    __table_args__ = (Index('ix_message_reaction_message_id', 'message_id'),)
     id = Column(Text, primary_key=True, unique=True)
     user_id = Column(Text)
     message_id = Column(Text)
@@ -36,6 +52,10 @@ class MessageReactionModel(BaseModel):
 
 class Message(Base):
     __tablename__ = 'message'
+    __table_args__ = (
+        Index('ix_message_channel_parent_created', 'channel_id', 'parent_id', 'created_at'),
+        Index('ix_message_parent_id', 'parent_id'),
+    )
     id = Column(Text, primary_key=True, unique=True)
 
     user_id = Column(Text)