[PATCH v1 1/1] box: fix assert with multikey hybrid index

[Kirill Shcherbatov]

Tarantool used to assume that offset_slot has an extension
iff field_map_get_offset is called with multikey_idx >= 0.
In fact, when some part of the index contains a multikey index
placeholder, tuple_compare_* routines pass a tuple_hint in
meaning of multikey index for each tuple_field_raw_by_part call,
even for regular key_part that doesn't have array index
placeholder (and, correspondingly, field_map extension).
Thus this assumption is invalid.

This patch uses the fact that field_map slots that have extensoin
store negative offset to distinguish multikey and normal usage
of the field_map_get_offset routine.

Closes #4234
---
http://github.com/tarantool/tarantool/tree/kshch/gh-4234-hybrid-multikey-index-parts-assert
https://github.com/tarantool/tarantool/issues/4234

 src/box/field_map.h           |  4 ++--
 test/engine/multikey.result   | 27 +++++++++++++++++++++++++++
 test/engine/multikey.test.lua | 10 ++++++++++
 3 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/src/box/field_map.h b/src/box/field_map.h
index b0dfeb4e4..2e2eea035 100644
--- a/src/box/field_map.h
+++ b/src/box/field_map.h
@@ -152,8 +152,8 @@ field_map_get_offset(const uint32_t *field_map, int32_t offset_slot,
 		     int multikey_idx)
 {
 	uint32_t offset;
-	if (multikey_idx != MULTIKEY_NONE && field_map[offset_slot] > 0) {
-		assert((int32_t)field_map[offset_slot] < 0);
+	if (multikey_idx != MULTIKEY_NONE && field_map[offset_slot] > 0 &&
+	    (int32_t)field_map[offset_slot] < 0) {
 		/**
 		 * The field_map extent has the following
 		 * structure: [size=N|slot1|slot2|..|slotN]
diff --git a/test/engine/multikey.result b/test/engine/multikey.result
index 1d5d9e200..6c763b2dd 100644
--- a/test/engine/multikey.result
+++ b/test/engine/multikey.result
@@ -753,3 +753,30 @@ i2:select()
 s:drop()
 ---
 ...
+-- Hybrid multikey index definiton.
+box.cfg{}
+---
+...
+s = box.schema.space.create('clients')
+---
+...
+s:format({{name='name', type='string'}, {name='phone', type='array'}, {name='p', type='string'}})
+---
+...
+name_idx = s:create_index('name_idx', {parts = {{'name', 'string'}}})
+---
+...
+phone_idx = s:create_index('phone_idx', {parts = {{'phone[*]', 'string'}, {'p', 'string'}}, unique=false})
+---
+...
+s:insert({"Genadiy", {"911"}, 'b'})
+---
+- ['Genadiy', ['911'], 'b']
+...
+s:insert({"Jorge", {"911", "89457609234"}, 'a'})
+---
+- ['Jorge', ['911', '89457609234'], 'a']
+...
+s:drop()
+---
+...
diff --git a/test/engine/multikey.test.lua b/test/engine/multikey.test.lua
index f32f49d2b..b236938cd 100644
--- a/test/engine/multikey.test.lua
+++ b/test/engine/multikey.test.lua
@@ -194,3 +194,13 @@ s:replace{2, {{2, 3}}}
 i2 = s:create_index('sk', {parts = {{2, 'unsigned', path = '[1][*]'}}})
 i2:select()
 s:drop()
+
+-- Hybrid multikey index definiton.
+box.cfg{}
+s = box.schema.space.create('clients')
+s:format({{name='name', type='string'}, {name='phone', type='array'}, {name='p', type='string'}})
+name_idx = s:create_index('name_idx', {parts = {{'name', 'string'}}})
+phone_idx = s:create_index('phone_idx', {parts = {{'phone[*]', 'string'}, {'p', 'string'}}, unique=false})
+s:insert({"Genadiy", {"911"}, 'b'})
+s:insert({"Jorge", {"911", "89457609234"}, 'a'})
+s:drop()
-- 
2.21.0