From 563692222707e78a6bdda6f91b98c40db8406000 Mon Sep 17 00:00:00 2001
From: Hongze Cheng <hzcheng@taosdata.com>
Date: Tue, 17 May 2022 02:52:46 +0000
Subject: [PATCH 1/2] fix: drop column

---
 source/dnode/vnode/src/meta/metaTable.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/source/dnode/vnode/src/meta/metaTable.c b/source/dnode/vnode/src/meta/metaTable.c
index 6bfcc34c85..1aec4185b0 100644
--- a/source/dnode/vnode/src/meta/metaTable.c
+++ b/source/dnode/vnode/src/meta/metaTable.c
@@ -420,7 +420,8 @@ static int metaAlterTableColumn(SMeta *pMeta, int64_t version, SVAlterTbReq *pAl
   // get table entry
   SDecoder dc = {0};
   tDecoderInit(&dc, pData, nData);
-  metaDecodeEntry(&dc, &entry);
+  ret = metaDecodeEntry(&dc, &entry);
+  ASSERT(ret == 0);
 
   if (entry.type != TSDB_NORMAL_TABLE) {
     terrno = TSDB_CODE_VND_INVALID_TABLE_ACTION;
@@ -468,11 +469,11 @@ static int metaAlterTableColumn(SMeta *pMeta, int64_t version, SVAlterTbReq *pAl
         goto _err;
       }
       pSchema->sver++;
-      pSchema->nCols--;
       tlen = (pSchema->nCols - iCol - 1) * sizeof(SSchema);
       if (tlen) {
         memmove(pColumn, pColumn + 1, tlen);
       }
+      pSchema->nCols--;
       break;
     case TSDB_ALTER_TABLE_UPDATE_COLUMN_BYTES:
       if (pColumn == NULL) {

From e1645ee19c203511368144ba2ad04d0fa2810d4e Mon Sep 17 00:00:00 2001
From: Hongze Cheng <hzcheng@taosdata.com>
Date: Tue, 17 May 2022 05:30:08 +0000
Subject: [PATCH 2/2] more alter table

---
 source/dnode/mnode/impl/src/mndStb.c    |  2 +-
 source/dnode/vnode/src/meta/metaTable.c | 35 +++++++++++++++++++++++--
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/source/dnode/mnode/impl/src/mndStb.c b/source/dnode/mnode/impl/src/mndStb.c
index 5a834f4d33..faa0d71d3b 100644
--- a/source/dnode/mnode/impl/src/mndStb.c
+++ b/source/dnode/mnode/impl/src/mndStb.c
@@ -386,7 +386,7 @@ static void *mndBuildVCreateStbReq(SMnode *pMnode, SVgObj *pVgroup, SStbObj *pSt
   req.schema.sver = pStb->version;
   req.schema.pSchema = pStb->pColumns;
   req.schemaTag.nCols = pStb->numOfTags;
-  req.schemaTag.nCols = 0;
+  req.schemaTag.sver = 1;
   req.schemaTag.pSchema = pStb->pTags;
 
   if (req.rollup) {
diff --git a/source/dnode/vnode/src/meta/metaTable.c b/source/dnode/vnode/src/meta/metaTable.c
index 1aec4185b0..9064085b2b 100644
--- a/source/dnode/vnode/src/meta/metaTable.c
+++ b/source/dnode/vnode/src/meta/metaTable.c
@@ -599,10 +599,41 @@ static int metaUpdateTableTagVal(SMeta *pMeta, int64_t version, SVAlterTbReq *pA
     goto _err;
   }
 
-  {
-    // TODO:
+  if (iCol == 0) {
+    // TODO : need to update tag index
   }
 
+  ctbEntry.version = version;
+  SKVRowBuilder kvrb = {0};
+  const SKVRow  pOldTag = (const SKVRow)ctbEntry.ctbEntry.pTags;
+  SKVRow        pNewTag = NULL;
+
+  tdInitKVRowBuilder(&kvrb);
+  for (int32_t i = 0; i < pTagSchema->nCols; i++) {
+    SSchema *pCol = &pTagSchema->pSchema[i];
+    if (iCol == i) {
+      tdAddColToKVRow(&kvrb, pCol->colId, pAlterTbReq->pTagVal, pAlterTbReq->nTagVal);
+    } else {
+      void *p = tdGetKVRowValOfCol(pOldTag, pCol->colId);
+      if (p) {
+        if (IS_VAR_DATA_TYPE(pCol->type)) {
+          tdAddColToKVRow(&kvrb, pCol->colId, p, varDataTLen(p));
+        } else {
+          tdAddColToKVRow(&kvrb, pCol->colId, p, pCol->bytes);
+        }
+      }
+    }
+  }
+
+  ctbEntry.ctbEntry.pTags = tdGetKVRowFromBuilder(&kvrb);
+  tdDestroyKVRowBuilder(&kvrb);
+
+  // save to table.db
+  metaSaveToTbDb(pMeta, &ctbEntry);
+
+  // save to uid.idx
+  tdbDbUpsert(pMeta->pUidIdx, &ctbEntry.uid, sizeof(tb_uid_t), &version, sizeof(version), &pMeta->txn);
+
   if (ctbEntry.pBuf) taosMemoryFree(ctbEntry.pBuf);
   if (stbEntry.pBuf) tdbFree(stbEntry.pBuf);
   tdbDbcClose(pTbDbc);