[Tarantool-patches] [PATCH 1/6] sql: refactor resulting set metadata
Vladislav Shpilevoy
v.shpilevoy at tarantool.org
Fri Nov 29 01:41:49 MSK 2019
Hi! Thanks for the patch!
How is your life, kids, wife, job? I hope everything
is good! Lets consider what can we do better here.
Below is just my own opinion and some of advice, nothing
obligatory or toxic!
See 6 tiny friendly comments below :) (no dot in the end = no toxic)
On 27/11/2019 13:15, Nikita Pettik wrote:
> Move names and types of resulting set to a separate structure. Simplify
> their storage by introducing separate members for name and type
> (previously names and types were stored in one char * array). It will
> allow us to add new metadata properties with ease.
>
> Needed for #4407
> ---
> src/box/sql/delete.c | 6 ++--
> src/box/sql/insert.c | 5 ++--
> src/box/sql/legacy.c | 2 +-
> src/box/sql/pragma.c | 14 ++++-----
> src/box/sql/prepare.c | 9 +++---
> src/box/sql/select.c | 60 ++++++++++++++++++--------------------
> src/box/sql/update.c | 6 ++--
> src/box/sql/vdbe.h | 28 ++++++++++--------
> src/box/sql/vdbeInt.h | 8 ++++-
> src/box/sql/vdbeapi.c | 81 +++++++++------------------------------------------
> src/box/sql/vdbeaux.c | 81 +++++++++++++++++++++++++++------------------------
> 11 files changed, 124 insertions(+), 176 deletions(-)
>
> diff --git a/src/box/sql/prepare.c b/src/box/sql/prepare.c
> index 0ecc676e2..2d3466cc7 100644
> --- a/src/box/sql/prepare.c
> +++ b/src/box/sql/prepare.c
> @@ -146,11 +146,10 @@ sqlPrepare(sql * db, /* Database handle. */
> sqlVdbeSetNumCols(sParse.pVdbe, name_count);
> for (int i = 0; i < name_count; i++) {
> int name_index = 2 * i + name_first;
> - sqlVdbeSetColName(sParse.pVdbe, i, COLNAME_NAME,
> - azColName[name_index], SQL_STATIC);
> - sqlVdbeSetColName(sParse.pVdbe, i, COLNAME_DECLTYPE,
> - azColName[name_index + 1],
> - SQL_STATIC);
> + vdbe_set_metadata_col_name(sParse.pVdbe, i,
> + azColName[name_index]);
> + vdbe_set_metadata_col_type(sParse.pVdbe, i,
> + azColName[name_index + 1]);
1. Lets fix this indentation.
> }
> }
>
> diff --git a/src/box/sql/select.c b/src/box/sql/select.c
> index 8f93edd16..d6b8a158f 100644
> --- a/src/box/sql/select.c
> +++ b/src/box/sql/select.c
> @@ -2828,7 +2824,7 @@ multiSelect(Parse * pParse, /* Parsing context */
> Select *pFirst = p;
> while (pFirst->pPrior)
> pFirst = pFirst->pPrior;
> - generateColumnNames(pParse,
> + generate_column_metadata(pParse,
> pFirst->pSrc,
> pFirst->pEList);
2. And this too.
> }
> diff --git a/src/box/sql/vdbe.h b/src/box/sql/vdbe.h
> index 582d48a1f..4142fb6ba 100644
> --- a/src/box/sql/vdbe.h
> +++ b/src/box/sql/vdbe.h
> @@ -248,7 +241,18 @@ void sqlVdbeResetStepResult(Vdbe *);
> void sqlVdbeRewind(Vdbe *);
> int sqlVdbeReset(Vdbe *);
> void sqlVdbeSetNumCols(Vdbe *, int);
> -int sqlVdbeSetColName(Vdbe *, int, int, const char *, void (*)(void *));
> +
> +/**
> + * Set the name of the idx'th column to be returned by the SQL
> + * statement. @name must be a pointer to a nul terminated string.
> + * This call must be made after a call to sqlVdbeSetNumCols().
> + */
> +int
> +vdbe_set_metadata_col_name(struct Vdbe *v, int col_idx, const char *name);
> +
> +int
> +vdbe_set_metadata_col_type(struct Vdbe *v, int col_idx, const char *type);
3. I think, that we should use one prefix for metadata
methods. You used 'vdbe_metadata_delete()' above, so lets
make it 'vdbe_metadata_*' everywhere. And these functions
will be
vdbe_metadata_set_col_name/type...
> diff --git a/src/box/sql/vdbeInt.h b/src/box/sql/vdbeInt.h
> index 0f32b4cd6..9ab3753cb 100644
> --- a/src/box/sql/vdbeInt.h
> +++ b/src/box/sql/vdbeInt.h
> @@ -394,7 +399,8 @@ struct Vdbe {
> Op *aOp; /* Space to hold the virtual machine's program */
> Mem *aMem; /* The memory locations */
> Mem **apArg; /* Arguments to currently executing user function */
> - Mem *aColName; /* Column names to return */
> + /** SQL metadata for SELECT queries. */
4. Looks like it can be emitted on DML too. I see
vdbe_set_metadata_col_name(v, 0, "rows updated") in
sqlUpdate(), and vdbe_set_metadata_col_name(v, 0, "rows deleted")
in sql_table_delete_from().
> + struct sql_column_metadata *metadata;
> Mem *pResultSet; /* Pointer to an array of results */
> VdbeCursor **apCsr; /* One element of this array for each open cursor */
> Mem *aVar; /* Values for the OP_Variable opcode. */
> diff --git a/src/box/sql/vdbeaux.c b/src/box/sql/vdbeaux.c
> index a1d658648..db11fbf33 100644
> --- a/src/box/sql/vdbeaux.c
> +++ b/src/box/sql/vdbeaux.c
> @@ -1827,6 +1827,18 @@ Cleanup(Vdbe * p)
> p->pResultSet = 0;
> }
>
> +void
> +vdbe_metadata_delete(struct Vdbe *v)
> +{
> + if (v->metadata != NULL) {
> + for (int i = 0; i < v->nResColumn; ++i) {
> + free((void *)v->metadata[i].name);
> + free((void *)v->metadata[i].type);
5. The necessity to do that cast basically makes 'const'
in the struct useless. Could you please make them just
char *, not const char *?
> + }
> + free(v->metadata);
> + }
> +}
> +
> /*
> * Set the number of result columns that will be returned by this SQL
> * statement. This is now set at compile time, rather than during
> @@ -1836,50 +1848,44 @@ Cleanup(Vdbe * p)
> +vdbe_set_metadata_col_name(struct Vdbe *p, int idx, const char *name)
> +{
> assert(idx < p->nResColumn);
> - assert(var < COLNAME_N);
> - if (p->db->mallocFailed) {
> - assert(!zName || xDel != SQL_DYNAMIC);
> + if (p->metadata[idx].name != NULL)
> + free((void *)p->metadata[idx].name);
> + p->metadata[idx].name = strdup(name);
> + if (p->metadata[idx].name == NULL) {
> + diag_set(OutOfMemory, strlen(name), "strdup", "name");
6. Len + 1. Dup allocates terminating zero too. In the next patches
too.
> return -1;
> }
> - assert(p->aColName != 0);
> - assert(var == COLNAME_NAME || var == COLNAME_DECLTYPE);
> - pColName = &(p->aColName[idx + var * p->nResColumn]);
> - rc = sqlVdbeMemSetStr(pColName, zName, -1, 1, xDel);
> - assert(rc != 0 || !zName || (pColName->flags & MEM_Term) != 0);
> - return rc;
> + return 0;
> +}
> +
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