feat: add aggregate example

.github/workflows/examples.yml

@@ -20,7 +20,7 @@ jobs:
       matrix:
         version: [10, 11, 12, 13]
         os: ["ubuntu-latest"]
-        examples: ["arrays", "bad_ideas", "bgworker", "bytea", "custom_types", "errors", "operators", "schemas", "shmem", "spi", "srf", "strings"]
+        examples: ["aggregate", "arrays", "bad_ideas", "bgworker", "bytea", "custom_types", "errors", "operators", "schemas", "shmem", "spi", "srf", "strings"]
 
     steps:
     - uses: actions/checkout@v2

pgx-examples/aggregate/.cargo/config

@@ -0,0 +1,3 @@
+[build]
+# Postgres symbols won't ve available until runtime
+rustflags = ["-C", "link-args=-Wl,-undefined,dynamic_lookup"]

pgx-examples/aggregate/.gitignore

@@ -0,0 +1,7 @@
+.DS_Store
+.idea/
+/target
+*.iml
+**/*.rs.bk
+Cargo.lock
+sql/*.generated.sql

pgx-examples/aggregate/Cargo.toml

@@ -0,0 +1,36 @@
+[package]
+name = "aggregate"
+version = "0.0.0"
+edition = "2018"
+
+[lib]
+crate-type = ["cdylib"]
+
+# remove this empty 'workspace' declaration if compiling outside of 'pgx'
+[workspace]
+
+[features]
+default = ["pg13"]
+pg10 = ["pgx/pg10", "pgx-tests/pg10" ]
+pg11 = ["pgx/pg11", "pgx-tests/pg11" ]
+pg12 = ["pgx/pg12", "pgx-tests/pg12" ]
+pg13 = ["pgx/pg13", "pgx-tests/pg13" ]
+pg_test = []
+
+[dependencies]
+pgx = "0.1.21"
+pgx-macros = "0.1.21"
+serde = "1.0.130"
+
+[dev-dependencies]
+pgx-tests = "0.1.21"
+
+# uncomment these if compiling outside of 'pgx'
+#[profile.dev]
+#panic = "unwind"
+#
+#[profile.release]
+#panic = "unwind"
+#opt-level = 3
+#lto = "fat"
+#codegen-units = 1

pgx-examples/aggregate/aggregate.control

@@ -0,0 +1,5 @@
+comment = 'aggregate:  Created by pgx'
+default_version = '1.0'
+module_pathname = '$libdir/aggregate'
+relocatable = false
+superuser = false

pgx-examples/aggregate/sql/load-order.txt

@@ -0,0 +1 @@
+lib.generated.sql

pgx-examples/aggregate/src/lib.rs

@@ -0,0 +1,116 @@
+use pgx::*;
+use std::{
+    str::FromStr,
+    ffi::CStr,
+};
+
+pg_module_magic!();
+
+#[derive(Copy, Clone, PostgresType)]
+#[pgvarlena_inoutfuncs]
+pub struct IntegerAvgState {
+    sum: i32,
+    n: i32,
+}
+
+impl PgVarlenaInOutFuncs for IntegerAvgState {
+    fn input(input: &CStr) -> PgVarlena<Self> {
+        let mut result = PgVarlena::<Self>::new();
+
+        let mut split = input.to_bytes().split(|b| *b == b',');
+        let sum = split.next().map(|value| 
+            i32::from_str(unsafe { std::str::from_utf8_unchecked(value) }).expect("invalid i32")
+        ).expect("expected sum");
+        let n = split.next().map(|value| 
+            i32::from_str(unsafe { std::str::from_utf8_unchecked(value) }).expect("invalid i32")
+        ).expect("expected n");
+
+        result.sum = sum;
+        result.n = n;
+
+        result
+    }
+    fn output(&self, buffer: &mut StringInfo) {
+        buffer.push_str(&format!("{},{}", self.sum, self.n));
+    }
+}
+
+
+impl Default for IntegerAvgState {
+    fn default() -> Self {
+        Self { sum: 0, n: 0 }
+    }
+}
+
+impl IntegerAvgState {
+    fn acc(&self, v: i32) -> PgVarlena<Self> {
+        let mut new = PgVarlena::<Self>::new();
+        new.sum = self.sum + v;
+        new.n = self.n + 1;
+        new
+    }
+    fn finalize(&self) -> i32 {
+        self.sum / self.n
+    }
+}
+
+#[pg_extern]
+fn integer_avg_state_func(
+    internal_state: PgVarlena<IntegerAvgState>,
+    next_data_value: i32,
+) -> PgVarlena<IntegerAvgState> {
+    internal_state.acc(next_data_value)
+}
+
+#[pg_extern]
+fn integer_avg_final_func(internal_state: PgVarlena<IntegerAvgState>) -> i32 {
+    internal_state.finalize()
+}
+
+extension_sql!(
+    r#"
+    CREATE AGGREGATE DEMOAVG (integer)
+    (
+        sfunc = integer_avg_state_func,
+        stype = IntegerAvgState,
+        finalfunc = integer_avg_final_func,
+        initcond = '0,0'
+    );
+    "#
+);
+
+#[cfg(any(test, feature = "pg_test"))]
+mod tests {
+    use pgx::*;
+    use crate::IntegerAvgState;
+
+    #[pg_test]
+    fn test_integer_avg_state() {
+        assert_eq!(
+            2,
+            IntegerAvgState::default().acc(1).acc(2).acc(3).finalize()
+        );
+    }
+
+    #[pg_test]
+    fn test_integer_avg_state_sql() {
+        Spi::run("CREATE TABLE demo_table (value INTEGER);");
+        Spi::run("INSERT INTO demo_table (value) VALUES (1), (2), (3);");
+        let retval =
+            Spi::get_one::<i32>("SELECT DEMOAVG(value) FROM demo_table;")
+                .expect("SQL select failed");
+        assert_eq!(retval, 2);
+    }
+}
+
+#[cfg(test)]
+pub mod pg_test {
+    pub fn setup(_options: Vec<&str>) {
+        // perform one-off initialization when the pg_test framework starts
+    }
+
+    pub fn postgresql_conf_options() -> Vec<&'static str> {
+        // return any postgresql.conf settings that are required for your tests
+        vec![]
+    }
+}

pgx-examples/custom_types/src/fixed_size.rs

@@ -10,7 +10,7 @@ pub struct FixedF32Array {
 
 impl PgVarlenaInOutFuncs for FixedF32Array {
     fn input(input: &CStr) -> PgVarlena<Self> {
-        let mut result = PgVarlena::<FixedF32Array>::new();
+        let mut result = PgVarlena::<Self>::new();
 
         for (i, value) in input.to_bytes().split(|b| *b == b',').enumerate() {
             result.array[i] =