diff --git a/ldms/src/decomp/static/decomp_static.c b/ldms/src/decomp/static/decomp_static.c
index 63c2616a6..c8bcb3b02 100644
--- a/ldms/src/decomp/static/decomp_static.c
+++ b/ldms/src/decomp/static/decomp_static.c
@@ -111,8 +111,7 @@ mval_from_json(ldms_mval_t *v,
 	dst.type = mtype;
 	jtype = json_typeof(jent);
 
-	if ((jtype == JSON_STRING && mtype != LDMS_V_CHAR_ARRAY) ||
-			(mtype == LDMS_V_CHAR_ARRAY && jtype != JSON_STRING)) {
+	if ((mtype == LDMS_V_CHAR_ARRAY && jtype != JSON_STRING)) {
 		snprintf(err_buf, err_sz, "string type must have string value");
 		return EINVAL;
 	}
@@ -132,6 +131,13 @@ mval_from_json(ldms_mval_t *v,
 			return EINVAL;
 		}
 		break;
+	case JSON_STRING:
+		if (mtype != LDMS_V_CHAR && mtype != LDMS_V_CHAR_ARRAY) {
+			snprintf(err_buf, err_sz,
+				 "string value must have 'char' or 'char_array' type");
+			return EINVAL;
+		}
+		break;
 	default:
 		snprintf(err_buf, err_sz, "Unsupported JSON value");
 		return EINVAL;
@@ -289,6 +295,7 @@ typedef struct decomp_static_mid_rbn_s {
 		enum ldms_value_type mtype;
 		size_t array_len;
 		enum ldms_value_type rec_mtype;
+		enum ldms_value_type le_mtype;
 #if 0
 		size_t mval_size;	/* Size of this mval */
 		off_t mval_offset;	/* Offset into mval memory for this column */
@@ -874,6 +881,7 @@ static int resolve_col(struct resolve_ctxt_s *ctxt,
 	col_mid->array_len = -1;
 	col_mid->rec_mid = -EINVAL;
 	col_mid->rec_mtype = LDMS_V_NONE;
+	col_mid->le_mtype = LDMS_V_NONE;
 
 	src = cfg_col->src;
 
@@ -915,11 +923,12 @@ static int resolve_col(struct resolve_ctxt_s *ctxt,
 	if (mid < 0) {
 		/* This is a fill candidate, must have a type and if
 		 * an array a length */
-		if (cfg_col->type == LDMS_V_NONE) {
+		if (!cfg_col->fill) {
 			ldmsd_log(LDMSD_LERROR,
 				"strgp '%s': col[src] '%s' does not exist in "
-				"the set and the 'type' is not specified.\n",
-				ctxt->strgp->obj.name, cfg_col->src);
+				"the set '%s' and the 'fill' is not specified.\n",
+				ctxt->strgp->obj.name, cfg_col->src,
+				ldms_set_name_get(ctxt->set));
 			rc = EINVAL;
 			goto err;
 		}
@@ -940,7 +949,7 @@ static int resolve_col(struct resolve_ctxt_s *ctxt,
 
 	mtype = ldms_metric_type_get(ctxt->set, mid);
 	mlen = ldms_metric_array_get_len(ctxt->set, mid);
-	assert(mlen >= 0);
+	ASSERT_RETURN((!ldms_type_is_array(mtype)) || mlen);
 
 	if (LDMS_V_NONE < mtype && mtype <= LDMS_V_D64_ARRAY) {
 		/* Primitives & array of primitives. We have mlen, mtype and
@@ -966,7 +975,7 @@ static int resolve_col(struct resolve_ctxt_s *ctxt,
 	/* handling LIST */
 	lh = ldms_metric_get(ctxt->set, mid);
 	le = ldms_list_first(ctxt->set, lh, &le_mtype, &mlen);
-	assert(mlen);
+	ASSERT_RETURN((!ldms_type_is_array(le_mtype)) || mlen);
 	if (!le) {
 		/* list empty. can't init yet */
 		ldmsd_log(LDMSD_LERROR,
@@ -1004,7 +1013,7 @@ static int resolve_col(struct resolve_ctxt_s *ctxt,
 		goto err;
 	}
 	rec_mtype = ldms_record_metric_type_get(le, rec_mid, &mlen);
-	assert(mlen);
+	ASSERT_RETURN((!ldms_type_is_array(rec_mtype)) || mlen);
 	goto commit;
 
 rec_array_routine:
@@ -1028,7 +1037,7 @@ static int resolve_col(struct resolve_ctxt_s *ctxt,
 		goto err;
 	}
 	rec_mtype = ldms_record_metric_type_get(rec, rec_mid, &mlen);
-	assert(mlen);
+	ASSERT_RETURN((!ldms_type_is_array(rec_mtype)) || mlen);
 	/* fall through to commit */
 
 commit:
@@ -1036,21 +1045,29 @@ static int resolve_col(struct resolve_ctxt_s *ctxt,
 	col_mid->mid = mid;
 	col_mid->mtype = mtype;
 	col_mid->array_len = mlen;
-	assert(mlen);
+	col_mid->le_mtype = le_mtype;
 	if (rec_mid >= 0) {
 		col_mid->rec_mid = rec_mid;
 		col_mid->rec_mtype = rec_mtype;
+		ASSERT_RETURN((!ldms_type_is_array(rec_mtype)) || mlen);
+	} else {
 	}
 
 	/* commit to cfg_col */
 
-	assert(mtype != LDMS_V_NONE);
+	ASSERT_RETURN(mtype != LDMS_V_NONE);
 	if (cfg_col->type == LDMS_V_NONE) {
-		cfg_col->type = rec_mid>=0?rec_mtype:mtype;
+		if (rec_mid >= 0)
+			cfg_col->type = rec_mtype;
+		else if (mtype == LDMS_V_LIST)
+			cfg_col->type = le_mtype;
+		else
+			cfg_col->type = mtype;
 	}
 	if (0 == cfg_col->array_len) {
-		assert(mlen >= 0);
 		cfg_col->array_len = mlen;
+		ASSERT_RETURN((!ldms_type_is_array(cfg_col->type)) ||
+				cfg_col->array_len);
 	}
 	if (0 == cfg_col->mval_size) {
 		cfg_col->mval_offset = ctxt->mval_offset;
@@ -1065,7 +1082,7 @@ static int resolve_col(struct resolve_ctxt_s *ctxt,
 
 next:
 
-	assert(special || cfg_col->mval_size);
+	ASSERT_RETURN(special || cfg_col->mval_size);
 	/* update row schema digest */
 	EVP_DigestUpdate(ctxt->evp_ctx, cfg_col->dst, strlen(cfg_col->dst));
 	EVP_DigestUpdate(ctxt->evp_ctx, &cfg_col->type, sizeof(cfg_col->type));
@@ -1193,7 +1210,7 @@ static void assign_value(ldmsd_col_t dst, ldmsd_col_t src)
 	}
 	switch (dst->type) {
 	case LDMS_V_CHAR:
-		dst->mval->v_char = ldms_mval_as_s8(src->mval, src->type, 0);
+		dst->mval->v_char = ldms_mval_as_char(src->mval, src->type, 0);
 		break;
 	case LDMS_V_U8:
 		dst->mval->v_u8 = ldms_mval_as_u8(src->mval, src->type, 0);
@@ -1750,6 +1767,7 @@ static int decomp_static_decompose(ldmsd_strgp_t strgp, ldms_set_t set,
 	const char *producer;
 	const char *instance;
 	int producer_len, instance_len;
+	union ldms_value zfill = {0}; /* zero value as default "fill" */
 
 	if (!TAILQ_EMPTY(row_list))
 		return EINVAL;
@@ -1922,8 +1940,15 @@ static int decomp_static_decompose(ldmsd_strgp_t strgp, ldms_set_t set,
 		col_mvals_fill:
 			mcol->le = NULL;
 			mcol->mval = cfg_row->cols[j].fill;
-			mcol->mtype = cfg_row->cols[j].type;
-			mcol->array_len = cfg_row->cols[j].fill_len;
+			if (mcol->mval) {
+				mcol->mtype = cfg_row->cols[j].type;
+				mcol->array_len = cfg_row->cols[j].fill_len;
+			} else {
+				/* no "fill" specified, use default "fill" */
+				mcol->mval = &zfill;
+				mcol->array_len = 1;
+				mcol->mtype = cfg_row->cols[j].type;
+			}
 		}
 
 	make_row: /* make/expand rows according to col_mvals */
@@ -2037,8 +2062,14 @@ static int decomp_static_decompose(ldmsd_strgp_t strgp, ldms_set_t set,
 
 		col_fill:
 			mcol->mval = cfg_row->cols[j].fill;
-			mcol->array_len = row->cols[j].array_len;
-			mcol->mtype = cfg_row->cols[j].type;
+			if (mcol->mval) {
+				mcol->array_len = row->cols[j].array_len;
+				mcol->mtype = cfg_row->cols[j].type;
+			} else {
+				mcol->mval = &zfill;
+				mcol->array_len = 1;
+				mcol->mtype = cfg_row->cols[j].type;
+			}
 		}
 
 		if (cfg_row->op_present) {