add bin for generating sql

When you add a column in PG on a partitioned table the
new column will not be created on existing partitions.

New partitions created will have the new column.

Author: ryansmith3136

be/src/bin/add_col.rs

@@ -0,0 +1,46 @@
+use clap::Parser;
+use deadpool_postgres::Client;
+
+async fn tables(pg: &Client, prefix: &str) -> Result<Vec<String>, tokio_postgres::Error> {
+    let rows = pg
+        .query(
+            "select relname from pg_class
+             where relkind = 'r'
+               and relname like $1 || '%'
+             order by relname",
+            &[&prefix],
+        )
+        .await?;
+    Ok(rows.into_iter().map(|r| r.get::<_, String>(0)).collect())
+}
+
+async fn alter_table(table_name: &str, new_column: &str) -> String {
+    format!("ALTER TABLE {table_name} ADD COLUMN {new_column};")
+}
+
+#[derive(Clone, Debug, Parser)]
+struct Args {
+    #[arg(
+        long = "pg-be",
+        env = "PG_URL",
+        default_value = "postgres://localhost/be"
+    )]
+    pg_url: String,
+
+    #[arg(short = 't')]
+    table_name: String,
+
+    #[arg(short = 'c')]
+    column_desc: String,
+}
+
+#[tokio::main]
+async fn main() {
+    let args = Args::parse();
+    let pool = shared::pg::new_pool(&args.pg_url, 2).expect("pg_be pool");
+    let pg = pool.get().await.expect("backend pool");
+    let tables = tables(&pg, &args.table_name).await.unwrap();
+    for table in &tables {
+        println!("{}", alter_table(table, &args.column_desc).await);
+    }
+}