[tarantool-patches] [PATCH v2 6/6] sql: set column types for EXPLAIN and PRAGMA

[imeevma@tarantool.org]

Hi! Thank you for review! My answers and new patch below.

> 1. You rewrote this function almost completely. Usually in
> such a case we reformat the function into Tarantool code style.
>
Squashed review fixes.

> 2. I see that sql_pragma_table_stats returns rows of different types
> of the same columns. First row has 4 columns with types "ssii", other
> rows have 3 columns "sii". I think, all rows should have the same
> number of columns of the same types. Also, the first row actually
> duplicates the second - they both describe the primary index.
>
> Please, consult server team chat what to do with it. I think, that we
> should always return 3 columns "sii": index name, avg tuple size, index size.
> So we just should delete the current first row.
>
After some discussion in server chat it was decided to left as it
is, at least for now.

> 3. I do not see where case_sensitive_like returns anything.
> Looks like it is has 'void' return type. So it should not
> have any out names/types. The same about all other pragmas
> below. Or am I wrong?
>
Fixed in one of the patches in the patch-set.

commit f7265e12b4ad98ea4d92487bc258f6c62db2d9b3
Author: Mergen Imeev <imeevma@gmail.com>
Date:   Wed Dec 5 14:30:49 2018 +0300

    sql: set column types for EXPLAIN and PRAGMA
    
    Currently, EXPLAIN and PRAGMA do not set the column types for the
    result. This is incorrect, since any returned row must have a
    column type. This patch defines the types for these columns.
    
    Closes #3832

diff --git a/src/box/execute.c b/src/box/execute.c
index 3a6cadf..d3adacb 100644
--- a/src/box/execute.c
+++ b/src/box/execute.c
@@ -550,11 +550,12 @@ sql_get_description(struct sqlite3_stmt *stmt, struct obuf *out,
    const char *name = sqlite3_column_name(stmt, i);
    const char *type = sqlite3_column_datatype(stmt, i);
    /*
-    * Can not fail, since all column names are
-    * preallocated during prepare phase and the
+    * Can not fail, since all column names and types
+    * are preallocated during prepare phase and the
     * column_name simply returns them.
     */
    assert(name != NULL);
+   assert(type != NULL);
    size += mp_sizeof_str(strlen(name));
    size += mp_sizeof_str(strlen(type));
    char *pos = (char *) obuf_alloc(out, size);
diff --git a/src/box/sql/pragma.c b/src/box/sql/pragma.c
index fc87976..eb8a69e 100644
--- a/src/box/sql/pragma.c
+++ b/src/box/sql/pragma.c
@@ -112,25 +112,20 @@ sqlite3GetBoolean(const char *z, u8 dflt)
  * the rest of the file if PRAGMAs are omitted from the build.
  */
 
-/*
- * Set result column names for a pragma.
- */
+/** Set result column names and types for a pragma. */
 static void
-setPragmaResultColumnNames(Vdbe * v, /* The query under construction */
-        const PragmaName * pPragma /* The pragma */
-    )
+vdbe_set_pragma_result_columns(struct Vdbe *v, const struct PragmaName *pragma)
 {
- u8 n = pPragma->nPragCName;
- sqlite3VdbeSetNumCols(v, n == 0 ? 1 : n);
- if (n == 0) {
-   sqlite3VdbeSetColName(v, 0, COLNAME_NAME, pPragma->zName,
+ int n = pragma->nPragCName;
+ assert(n > 0);
+ sqlite3VdbeSetNumCols(v, n);
+ for (int i = 0, j = pragma->iPragCName; i < n; ++i) {
+   /* Value of j is index of column name in array */
+   sqlite3VdbeSetColName(v, i, COLNAME_NAME, pragCName[j++],
+             SQLITE_STATIC);
+   /* Value of j is index of column type in array */
+   sqlite3VdbeSetColName(v, i, COLNAME_DECLTYPE, pragCName[j++],
              SQLITE_STATIC);
- } else {
-   int i, j;
-   for (i = 0, j = pPragma->iPragCName; i < n; i++, j++) {
-     sqlite3VdbeSetColName(v, i, COLNAME_NAME, pragCName[j],
-               SQLITE_STATIC);
-   }
  }
 }
 
@@ -473,16 +468,14 @@ sqlite3Pragma(Parse * pParse, Token * pId,  /* First part of [schema.]id field */
  }
  /* Register the result column names for pragmas that return results */
  if ((pPragma->mPragFlg & PragFlg_NoColumns) == 0
-     && ((pPragma->mPragFlg & PragFlg_NoColumns1) == 0 || zRight == 0)
-     ) {
-   setPragmaResultColumnNames(v, pPragma);
- }
+     && ((pPragma->mPragFlg & PragFlg_NoColumns1) == 0 || zRight == 0))
+   vdbe_set_pragma_result_columns(v, pPragma);
  /* Jump to the appropriate pragma handler */
  switch (pPragma->ePragTyp) {
 
  case PragTyp_FLAG:{
      if (zRight == 0) {
-       setPragmaResultColumnNames(v, pPragma);
+       vdbe_set_pragma_result_columns(v, pPragma);
        returnSingleInt(v,
            (user_session->
             sql_flags & pPragma->iArg) !=
diff --git a/src/box/sql/pragma.h b/src/box/sql/pragma.h
index 11a2e05..28e983e 100644
--- a/src/box/sql/pragma.h
+++ b/src/box/sql/pragma.h
@@ -27,50 +27,142 @@
 #define PragFlg_SchemaOpt  0x40  /* Schema restricts name search if present */
 #define PragFlg_SchemaReq  0x80  /* Schema required - "main" is default */
 
-/* Names of columns for pragmas that return multi-column result
- * or that return single-column results where the name of the
- * result column is different from the name of the pragma
+/**
+ * Column names and types for pragmas. The type of the column is
+ * the following value after its name.
  */
 static const char *const pragCName[] = {
  /* Used by: table_info */
  /*   0 */ "cid",
- /*   1 */ "name",
- /*   2 */ "type",
- /*   3 */ "notnull",
- /*   4 */ "dflt_value",
- /*   5 */ "pk",
+ /*   1 */ "INTEGER",
+ /*   2 */ "name",
+ /*   3 */ "TEXT",
+ /*   4 */ "type",
+ /*   3 */ "TEXT",
+ /*   6 */ "notnull",
+ /*   1 */ "INTEGER",
+ /*   8 */ "dflt_value",
+ /*   9 */ "TEXT",
+ /*  10 */ "pk",
+ /*  11 */ "INTEGER",
  /* Used by: stats */
- /*   6 */ "table",
- /*   7 */ "index",
- /*   8 */ "width",
- /*   9 */ "height",
+ /*  12 */ "table",
+ /*  13 */ "TEXT",
+ /*  14 */ "index",
+ /*  15 */ "TEXT",
+ /*  16 */ "width",
+ /*  17 */ "INTEGER",
+ /*  18 */ "height",
+ /*  19 */ "INTEGER",
  /* Used by: index_info */
- /*  10 */ "seqno",
- /*  11 */ "cid",
- /*  12 */ "name",
- /*  13 */ "desc",
- /*  14 */ "coll",
- /*  15 */ "type",
+ /*  20 */ "seqno",
+ /*  21 */ "INTEGER",
+ /*  22 */ "cid",
+ /*  23 */ "INTEGER",
+ /*  24 */ "name",
+ /*  25 */ "TEXT",
+ /*  26 */ "desc",
+ /*  27 */ "INTEGER",
+ /*  28 */ "coll",
+ /*  29 */ "TEXT",
+ /*  30 */ "type",
+ /*  31 */ "TEXT",
  /* Used by: index_list */
- /*  16 */ "seq",
- /*  17 */ "name",
- /*  18 */ "unique",
- /*  19 */ "origin",
- /*  20 */ "partial",
+ /*  32 */ "seq",
+ /*  33 */ "INTEGER",
+ /*  34 */ "name",
+ /*  35 */ "TEXT",
+ /*  36 */ "unique",
+ /*  37 */ "INTEGER",
+ /*  38 */ "origin",
+ /*  39 */ "TEXT",
+ /*  40 */ "partial",
+ /*  41 */ "INTEGER",
  /* Used by: collation_list */
- /*  21 */ "seq",
- /*  22 */ "name",
+ /*  42 */ "seq",
+ /*  43 */ "INTEGER",
+ /*  44 */ "name",
+ /*  45 */ "TEXT",
  /* Used by: foreign_key_list */
- /*  23 */ "id",
- /*  24 */ "seq",
- /*  25 */ "table",
- /*  26 */ "from",
- /*  27 */ "to",
- /*  28 */ "on_update",
- /*  29 */ "on_delete",
- /*  30 */ "match",
+ /*  46 */ "id",
+ /*  47 */ "INTEGER",
+ /*  48 */ "seq",
+ /*  49 */ "INTEGER",
+ /*  50 */ "table",
+ /*  51 */ "TEXT",
+ /*  52 */ "from",
+ /*  53 */ "TEXT",
+ /*  54 */ "to",
+ /*  55 */ "TEXT",
+ /*  56 */ "on_update",
+ /*  57 */ "TEXT",
+ /*  58 */ "on_delete",
+ /*  59 */ "TEXT",
+ /*  60 */ "match",
+ /*  61 */ "TEXT",
  /* Used by: busy_timeout */
- /*  31 */ "timeout",
+ /*  62 */ "timeout",
+ /*  63 */ "INTEGER",
+ /* Used by: case_sensitive_like */
+ /*  64 */ "case_sensitive_like",
+ /*  65 */ "INTEGER",
+ /* Used by: count_changes */
+ /*  66 */ "count_changes",
+ /*  67 */ "INTEGER",
+ /* Used by: defer_foreign_keys */
+ /*  68 */ "defer_foreign_keys",
+ /*  69 */ "INTEGER",
+ /* Used by: full_column_names */
+ /*  70 */ "full_column_names",
+ /*  71 */ "INTEGER",
+ /* Used by: parser_trace */
+ /*  72 */ "parser_trace",
+ /*  73 */ "INTEGER",
+ /* Used by: query_only */
+ /*  74 */ "query_only",
+ /*  75 */ "INTEGER",
+ /* Used by: read_uncommitted */
+ /*  76 */ "read_uncommitted",
+ /*  77 */ "INTEGER",
+ /* Used by: recursive_triggers */
+ /*  78 */ "recursive_triggers",
+ /*  79 */ "INTEGER",
+ /* Used by: reverse_unordered_selects */
+ /*  80 */ "reverse_unordered_selects",
+ /*  81 */ "INTEGER",
+ /* Used by: select_trace */
+ /*  82 */ "select_trace",
+ /*  83 */ "INTEGER",
+ /* Used by: short_column_names */
+ /*  84 */ "short_column_names",
+ /*  85 */ "INTEGER",
+ /* Used by: sql_compound_select_limit */
+ /*  86 */ "sql_compound_select_limit",
+ /*  87 */ "INTEGER",
+ /* Used by: sql_default_engine */
+ /*  88 */ "sql_default_engine",
+ /*  89 */ "TEXT",
+ /* Used by: sql_trace */
+ /*  90 */ "sql_trace",
+ /*  91 */ "INTEGER",
+ /* Used by: vdbe_addoptrace */
+ /*  92 */ "vdbe_addoptrace",
+ /*  93 */ "INTEGER",
+ /* Used by: vdbe_debug */
+ /*  94 */ "vdbe_debug",
+ /*  95 */ "INTEGER",
+ /* Used by: vdbe_eqp */
+ /*  96 */ "vdbe_eqp",
+ /*  97 */ "INTEGER",
+ /* Used by: vdbe_listing */
+ /*  98 */ "vdbe_listing",
+ /*  99 */ "INTEGER",
+ /* Used by: vdbe_trace */
+ /*  100 */ "vdbe_trace",
+ /*  101 */ "INTEGER",
+ /* Used by: where_trace */
+ /*  102 */ "where_trace",
+ /*  103 */ "INTEGER",
 };
 
 /* Definitions of all built-in pragmas */
@@ -79,7 +171,7 @@ typedef struct PragmaName {
  u8 ePragTyp;    /* PragTyp_XXX value */
  u8 mPragFlg;    /* Zero or more PragFlg_XXX values */
  u8 iPragCName;    /* Start of column names in pragCName[] */
- u8 nPragCName;    /* Num of col names. 0 means use pragma name */
+ u8 nPragCName;    /* Num of col names. */
  u32 iArg;   /* Extra argument */
 } PragmaName;
 /**
@@ -90,112 +182,112 @@ static const PragmaName aPragmaName[] = {
  { /* zName:     */ "busy_timeout",
   /* ePragTyp:  */ PragTyp_BUSY_TIMEOUT,
   /* ePragFlg:  */ PragFlg_Result0,
-  /* ColNames:  */ 31, 1,
+  /* ColNames:  */ 62, 1,
   /* iArg:      */ 0},
  { /* zName:     */ "case_sensitive_like",
   /* ePragTyp:  */ PragTyp_CASE_SENSITIVE_LIKE,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 64, 1,
   /* iArg:      */ SQLITE_LikeIsCaseSens},
  { /* zName:     */ "collation_list",
   /* ePragTyp:  */ PragTyp_COLLATION_LIST,
   /* ePragFlg:  */ PragFlg_Result0,
-  /* ColNames:  */ 21, 2,
+  /* ColNames:  */ 42, 2,
   /* iArg:      */ 0},
  { /* zName:     */ "count_changes",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 66, 1,
   /* iArg:      */ SQLITE_CountRows},
  { /* zName:     */ "defer_foreign_keys",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 68, 1,
   /* iArg:      */ SQLITE_DeferFKs},
  { /* zName:     */ "foreign_key_list",
   /* ePragTyp:  */ PragTyp_FOREIGN_KEY_LIST,
   /* ePragFlg:  */
   PragFlg_NeedSchema | PragFlg_Result1 | PragFlg_SchemaOpt,
-  /* ColNames:  */ 23, 8,
+  /* ColNames:  */ 46, 8,
   /* iArg:      */ 0},
  { /* zName:     */ "full_column_names",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 70, 1,
   /* iArg:      */ SQLITE_FullColNames},
  { /* zName:     */ "index_info",
   /* ePragTyp:  */ PragTyp_INDEX_INFO,
   /* ePragFlg:  */
   PragFlg_NeedSchema | PragFlg_Result1 | PragFlg_SchemaOpt,
-  /* ColNames:  */ 10, 6,
+  /* ColNames:  */ 20, 6,
   /* iArg:      */ 1},
  { /* zName:     */ "index_list",
   /* ePragTyp:  */ PragTyp_INDEX_LIST,
   /* ePragFlg:  */
   PragFlg_NeedSchema | PragFlg_Result1 | PragFlg_SchemaOpt,
-  /* ColNames:  */ 16, 5,
+  /* ColNames:  */ 32, 5,
   /* iArg:      */ 0},
 #if defined(SQLITE_DEBUG)
  { /* zName:     */ "parser_trace",
   /* ePragTyp:  */ PragTyp_PARSER_TRACE,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 72, 1,
   /* iArg:      */ SQLITE_ParserTrace},
 #endif
  { /* zName:     */ "query_only",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 74, 1,
   /* iArg:      */ SQLITE_QueryOnly},
  { /* zName:     */ "read_uncommitted",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 76, 1,
   /* iArg:      */ SQLITE_ReadUncommitted},
  { /* zName:     */ "recursive_triggers",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 78, 1,
   /* iArg:      */ SQLITE_RecTriggers},
  { /* zName:     */ "reverse_unordered_selects",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 80, 1,
   /* iArg:      */ SQLITE_ReverseOrder},
 #if defined(SQLITE_ENABLE_SELECTTRACE)
  { /* zName:     */ "select_trace",
  /* ePragTyp:  */ PragTyp_FLAG,
  /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
- /* ColNames:  */ 0, 0,
+ /* ColNames:  */ 82, 1,
  /* iArg:      */ SQLITE_SelectTrace},
 #endif
  { /* zName:     */ "short_column_names",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 84, 1,
   /* iArg:      */ SQLITE_ShortColNames},
  { /* zName:     */ "sql_compound_select_limit",
  /* ePragTyp:  */ PragTyp_COMPOUND_SELECT_LIMIT,
  /* ePragFlg:  */ PragFlg_Result0,
- /* ColNames:  */ 0, 0,
+ /* ColNames:  */ 86, 1,
  /* iArg:      */ 0},
  { /* zName:     */ "sql_default_engine",
   /* ePragTyp:  */ PragTyp_DEFAULT_ENGINE,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 88, 1,
   /* iArg:      */ 0},
 #if defined(SQLITE_DEBUG)
  { /* zName:     */ "sql_trace",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 90, 1,
   /* iArg:      */ SQLITE_SqlTrace},
 #endif
  { /* zName:     */ "stats",
   /* ePragTyp:  */ PragTyp_STATS,
   /* ePragFlg:  */
   PragFlg_NeedSchema | PragFlg_Result0 | PragFlg_SchemaReq,
-  /* ColNames:  */ 6, 4,
+  /* ColNames:  */ 12, 4,
   /* iArg:      */ 0},
  { /* zName:     */ "table_info",
   /* ePragTyp:  */ PragTyp_TABLE_INFO,
@@ -207,28 +299,28 @@ static const PragmaName aPragmaName[] = {
  { /* zName:     */ "vdbe_addoptrace",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 92, 1,
   /* iArg:      */ SQLITE_VdbeAddopTrace},
  { /* zName:     */ "vdbe_debug",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 94, 1,
   /* iArg:      */
   SQLITE_SqlTrace | SQLITE_VdbeListing | SQLITE_VdbeTrace},
  { /* zName:     */ "vdbe_eqp",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 96, 1,
   /* iArg:      */ SQLITE_VdbeEQP},
  { /* zName:     */ "vdbe_listing",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 98, 1,
   /* iArg:      */ SQLITE_VdbeListing},
  { /* zName:     */ "vdbe_trace",
   /* ePragTyp:  */ PragTyp_FLAG,
   /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
-  /* ColNames:  */ 0, 0,
+  /* ColNames:  */ 100, 1,
   /* iArg:      */ SQLITE_VdbeTrace},
 #endif
 #if defined(SQLITE_ENABLE_WHERETRACE)
@@ -236,7 +328,7 @@ static const PragmaName aPragmaName[] = {
  { /* zName:     */ "where_trace",
  /* ePragTyp:  */ PragTyp_FLAG,
  /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
- /* ColNames:  */ 0, 0,
+ /* ColNames:  */ 102, 1,
  /* iArg:      */ SQLITE_WhereTrace},
 #endif
 };
diff --git a/src/box/sql/prepare.c b/src/box/sql/prepare.c
index 824578e..87326da 100644
--- a/src/box/sql/prepare.c
+++ b/src/box/sql/prepare.c
@@ -54,7 +54,6 @@ sqlite3Prepare(sqlite3 * db,  /* Database handle. */
 {
  char *zErrMsg = 0;  /* Error message */
  int rc = SQLITE_OK; /* Result code */
- int i;      /* Loop counter */
  Parse sParse;   /* Parsing context */
  sql_parser_create(&sParse, db);
  sParse.pReprepare = pReprepare;
@@ -113,23 +112,48 @@ sqlite3Prepare(sqlite3 * db,  /* Database handle. */
 
  if (rc == SQLITE_OK && sParse.pVdbe && sParse.explain) {
    static const char *const azColName[] = {
-     "addr", "opcode", "p1", "p2", "p3", "p4", "p5",
-         "comment",
-     "selectid", "order", "from", "detail"
+     /*  0 */ "addr",
+     /*  1 */ "INTEGER",
+     /*  2 */ "opcode",
+     /*  3 */ "TEXT",
+     /*  4 */ "p1",
+     /*  5 */ "INTEGER",
+     /*  6 */ "p2",
+     /*  7 */ "INTEGER",
+     /*  8 */ "p3",
+     /*  9 */ "INTEGER",
+     /* 10 */ "p4",
+     /* 11 */ "TEXT",
+     /* 12 */ "p5",
+     /* 13 */ "TEXT",
+     /* 14 */ "comment",
+     /* 15 */ "TEXT",
+     /* 16 */ "selectid",
+     /* 17 */ "INTEGER",
+     /* 18 */ "order",
+     /* 19 */ "INTEGER",
+     /* 20 */ "from",
+     /* 21 */ "INTEGER",
+     /* 22 */ "detail",
+     /* 23 */ "TEXT",
    };
-   int iFirst, mx;
+
+   int name_first, name_count;
    if (sParse.explain == 2) {
-     sqlite3VdbeSetNumCols(sParse.pVdbe, 4);
-     iFirst = 8;
-     mx = 12;
+     name_first = 16;
+     name_count = 4;
    } else {
-     sqlite3VdbeSetNumCols(sParse.pVdbe, 8);
-     iFirst = 0;
-     mx = 8;
+     name_first = 0;
+     name_count = 8;
    }
-   for (i = iFirst; i < mx; i++) {
-     sqlite3VdbeSetColName(sParse.pVdbe, i - iFirst,
-               COLNAME_NAME, azColName[i],
+   sqlite3VdbeSetNumCols(sParse.pVdbe, name_count);
+   for (int i = 0; i < name_count; i++) {
+     int name_index = 2 * i + name_first;
+     sqlite3VdbeSetColName(sParse.pVdbe, i, COLNAME_NAME,
+               azColName[name_index],
+               SQLITE_STATIC);
+     sqlite3VdbeSetColName(sParse.pVdbe, i, COLNAME_DECLTYPE,
+               azColName[name_index + 1],
                SQLITE_STATIC);
    }
  }
diff --git a/test/sql/iproto.result b/test/sql/iproto.result
index 9ace282..e128001 100644
--- a/test/sql/iproto.result
+++ b/test/sql/iproto.result
@@ -821,6 +821,75 @@ box.sql.execute('DROP TABLE t1')
 cn:close()
 ---
 ...
+-- gh-3832: Some statements do not return column type
+box.sql.execute('CREATE TABLE t1(id INTEGER PRIMARY KEY)')
+---
+...
+cn = remote.connect(box.cfg.listen)
+---
+...
+-- PRAGMA:
+res = cn:execute("PRAGMA table_info(t1)")
+---
+...
+res.metadata
+---
+- - name: cid
+    type: INTEGER
+  - name: name
+    type: TEXT
+  - name: type
+    type: TEXT
+  - name: notnull
+    type: INTEGER
+  - name: dflt_value
+    type: TEXT
+  - name: pk
+    type: INTEGER
+...
+-- EXPLAIN
+res = cn:execute("EXPLAIN select 1")
+---
+...
+res.metadata
+---
+- - name: addr
+    type: INTEGER
+  - name: opcode
+    type: TEXT
+  - name: p1
+    type: INTEGER
+  - name: p2
+    type: INTEGER
+  - name: p3
+    type: INTEGER
+  - name: p4
+    type: TEXT
+  - name: p5
+    type: TEXT
+  - name: comment
+    type: TEXT
+...
+res = cn:execute("EXPLAIN QUERY PLAN select count(*) from t1")
+---
+...
+res.metadata
+---
+- - name: selectid
+    type: INTEGER
+  - name: order
+    type: INTEGER
+  - name: from
+    type: INTEGER
+  - name: detail
+    type: TEXT
+...
+cn:close()
+---
+...
+box.sql.execute('DROP TABLE t1')
+---
+...
 box.schema.user.revoke('guest', 'read,write,execute', 'universe')
 ---
 ...
diff --git a/test/sql/iproto.test.lua b/test/sql/iproto.test.lua
index 6640903..9f9a382 100644
--- a/test/sql/iproto.test.lua
+++ b/test/sql/iproto.test.lua
@@ -263,10 +263,26 @@ box.sql.execute('DROP TABLE t1')
 
 cn:close()
 
+-- gh-3832: Some statements do not return column type
+box.sql.execute('CREATE TABLE t1(id INTEGER PRIMARY KEY)')
+cn = remote.connect(box.cfg.listen)
+
+-- PRAGMA:
+res = cn:execute("PRAGMA table_info(t1)")
+res.metadata
+
+-- EXPLAIN
+res = cn:execute("EXPLAIN select 1")
+res.metadata
+res = cn:execute("EXPLAIN QUERY PLAN select count(*) from t1")
+res.metadata
+
+cn:close()
+box.sql.execute('DROP TABLE t1')
+
 box.schema.user.revoke('guest', 'read,write,execute', 'universe')
 box.schema.user.revoke('guest', 'create', 'space')
 space = nil
 
 -- Cleanup xlog
 box.snapshot()
-
-- 
2.7.4